user5866: Zen question-and-answers and talks like the ones described here don't seem like commonly accepted 'right speech'; yet, they are believed or intended to trigger spiritual progress.
In what way do such Zen interactions deliver benefits? For example, are they meant to be thought-provoking dissonance, discomfort and anger, and thereby cause dissatisfaction with habitually-held positions, and thereby create scope for spiritual progress?
Have the teachers specified (in any writings or talks) how to distinguish such dissonance-causing dialectics from "wrong speech" which causes hindrance in spiritual progress and delivers no spiritual benefits to listeners/readers?

user254: Andrei's answer said that the "antidote" could be used, for example, as follows,

So for example, if a Zen master notices that his student lost his fundamental sanity and has "gotten drunk on the shravaka wine" to use Dogen's parable, he might etc.

The following talk about Dogen's Shobogenzo mentions the context of "intoxication on the wine of the sravaka",

Talk on Master Dogen’s Shobogenzo
We’re on page 78, it’s fairly straightforward now. A description about
  discrimination against women in Buddhism.
Even in China, there was a stupid monk who made the following vow: “Through every life, in every age, I shall never look at a woman.”
  Upon what morality is this vow based? Is it based on secular morality?
  Is it based on the Buddha-Dharma? Is it based on the morality of
  non-Buddhists? Or is it based on the morality of heavenly demons? What
  wrong is there in a woman? What virtue is there in a man? Among bad
  people there are men who are bad people. Among good people there are
  women who are good people. Wanting to hear the Dharma, and wanting to
  get liberation, never depend on whether we are a man or a woman. When
  they have yet to cut delusion, men and women alike have yet to cut
  delusion. When they have cut delusion and experienced the principle,
  there is nothing at all to choose between a man and a woman.
So a very clear statement of equality, which unfortunately doesn’t
  exist in Japan, even Nishijima Roshi finds it difficult.
Moreover, if [a man] has vowed never to look at a woman, must he discard women even when vowing to save limitlessly many living beings?
  If he discards them he is not a bodhisattva. How much less [does he
  have] the Buddha’s compassion. This [vow] is just a drunken utterance
  caused by a deep intoxication on the wine of the sravaka.
In other words it’s a mental delusion.
Ch: What does the wine of the sravaka mean?
He just means the delusion of becoming enlightened. So he means the
  romantic idea that we attain some special state.
Neither human beings nor gods should believe this [vow] to be true.
He’s talking about that monk’s vow.

So I think that explains what "drunk on the shravaka wine" means (where Śrāvaka means "disciple").
Now in context perhaps you understand the effect of such speech and why and when it's effective.
It would work because (and only because) it's from the "drunken" disciple's formal teacher.
Also IMO perhaps it happens to be not incompatible with the formal rules of orthodox/traditional Right Speech of which one of the important definitions is (third item in the following list),

[1] "In the case of words that the Tathagata knows to be unfactual,
  untrue, unbeneficial (or: not connected with the goal), unendearing &
  disagreeable to others, he does not say them.
[2] "In the case of words that the Tathagata knows to be factual,
  true, unbeneficial, unendearing & disagreeable to others, he does not
  say them.
[3] "In the case of words that the Tathagata knows to be factual,
  true, beneficial, but unendearing & disagreeable to others, he has a
  sense of the proper time for saying them.
[4] "In the case of words that the Tathagata knows to be unfactual,
  untrue, unbeneficial, but endearing & agreeable to others, he does not
  say them.
[5] "In the case of words that the Tathagata knows to be factual,
  true, unbeneficial, but endearing & agreeable to others, he does not
  say them.
[6] "In the case of words that the Tathagata knows to be factual,
  true, beneficial, and endearing & agreeable to others, he has a sense
  of the proper time for saying them. Why is that? Because the Tathagata
  has sympathy for living beings."


user-1: First off, I think it's important to understand that Zen isn't something that should be greased up and crammed into the strictures of traditional Buddhist teachings.  Zen makes no overt attempt to follow the path as laid out in the Sutta Pitaka (i.e. in the Samanaphala Sutta) nor does it conform to the gradual training as described in texts like the Vissuddhimagga.  Topics like right action, sila, and virtue, while undoubtedly present in the Zen tradition, are meant to be arrived at through direct insight.  They are realities to be discovered, not guidelines to be followed during the initial stages of practice.   
The particular quotes that you are referring to are from two koans.  Specifically, they come from cases 1 and 21 from the koan collection entitled the Mumokan.  In Zen practice, koans are designed to point at some subtle experience of reality (i.e. big mind) that is often missed by our discursive and discriminating smaller minds.  They are not designed to be "thought provoking", nor do they try to be necessarily humorous, provoke anger, or instill discomfort.  They don't even try to cause dissonance.  For these reasons, they can often sound completely nonsensical.  In fact, koans are "none-sense" in the purest definition of the word.  No amount of reasoning will help you arrive at the experience they are pointing to.
That being said, koans are surgically precise.  They aren't just "right speech" they are "exact speech".  The experiences that a koan points to are ridiculously specific and, in the hands of a master teacher, can be used to great affect in awakening a student.  A good teacher knows exactly when to introduce a certain koan.  Like someone playing a game of Jenga, he knows just what block to pull out in order to get a student's whole mental edifice to come toppling down.  
All koans seek to awaken the mind.   Not a single word of them is tossed off haphazardly.  They are skillful means - upaya - but are functionally quite distinct from anything you might find in the Theravadan tradition.     

5866: <p>Zen question-and-answers and talks like the ones <a href="https://buddhism.stackexchange.com/questions/11424/are-there-examples-of-humor-and-irreverence-in-buddhist-scriptures/11510#11510">described here</a> don't seem like commonly accepted 'right speech'; yet, they are believed or intended to trigger spiritual progress.</p>

<p>In what way do such Zen interactions deliver benefits? For example, are they meant to be thought-provoking dissonance, discomfort and anger, and thereby cause dissatisfaction with habitually-held positions, and thereby create scope for spiritual progress?</p>

<p>Have the teachers specified (in any writings or talks) how to distinguish such dissonance-causing dialectics from "wrong speech" which causes hindrance in spiritual progress and delivers no spiritual benefits to listeners/readers?</p>
 254: <p>Andrei's answer said that the "antidote" could be used, for example, as follows,</p>

<blockquote>
  <p>So for example, if a Zen master notices that his student lost his fundamental sanity and has "gotten drunk on the shravaka wine" to use Dogen's parable, he might etc.</p>
</blockquote>

<p>The following talk about Dogen's <a href="https://en.wikipedia.org/wiki/Sh%C5%8Db%C5%8Dgenz%C5%8D" rel="nofollow">Shobogenzo</a> mentions the context of "intoxication on the wine of the sravaka",</p>

<blockquote>
  <p><a href="http://www.dogensangha.org.uk/Talks/8%20Rahai-tokuzui%204.pdf" rel="nofollow">Talk on Master Dogen’s Shobogenzo</a></p>
  
  <p>We’re on page 78, it’s fairly straightforward now. A description about
  discrimination against women in Buddhism.</p>
  
  <p><strong>Even in China, there was a stupid monk who made the following vow: “Through every life, in every age, I shall never look at a woman.”
  Upon what morality is this vow based? Is it based on secular morality?
  Is it based on the Buddha-Dharma? Is it based on the morality of
  non-Buddhists? Or is it based on the morality of heavenly demons? What
  wrong is there in a woman? What virtue is there in a man? Among bad
  people there are men who are bad people. Among good people there are
  women who are good people. Wanting to hear the Dharma, and wanting to
  get liberation, never depend on whether we are a man or a woman. When
  they have yet to cut delusion, men and women alike have yet to cut
  delusion. When they have cut delusion and experienced the principle,
  there is nothing at all to choose between a man and a woman.</strong></p>
  
  <p>So a very clear statement of equality, which unfortunately doesn’t
  exist in Japan, even Nishijima Roshi finds it difficult.</p>
  
  <p><strong>Moreover, if [a man] has vowed never to look at a woman, must he discard women even when vowing to save limitlessly many living beings?
  If he discards them he is not a bodhisattva. How much less [does he
  have] the Buddha’s compassion. This [vow] is just a drunken utterance
  caused by a deep intoxication on the wine of the sravaka.</strong></p>
  
  <p>In other words it’s a mental delusion.</p>
  
  <p><em>Ch: What does the wine of the sravaka mean?</em></p>
  
  <p>He just means the delusion of becoming enlightened. So he means the
  romantic idea that we attain some special state.</p>
  
  <p><strong>Neither human beings nor gods should believe this [vow] to be true.</strong></p>
  
  <p>He’s talking about that monk’s vow.</p>
</blockquote>

<p>So I think that explains what "drunk on the shravaka wine" means (where <em><a href="https://en.wikipedia.org/wiki/%C5%9Ar%C4%81vaka" rel="nofollow">Śrāvaka</a></em> means "disciple").</p>

<p>Now <em>in context</em> perhaps you understand the effect of such speech and why and when it's effective.</p>

<p>It would work because (and only because) it's from the "drunken" disciple's formal teacher.</p>

<p>Also IMO perhaps it happens to be not incompatible with the formal rules of orthodox/traditional <a href="http://www.accesstoinsight.org/ptf/dhamma/sacca/sacca4/samma-vaca/" rel="nofollow">Right Speech</a> of which one of the important definitions is (third item in the following list),</p>

<blockquote>
  <p>[1] "In the case of words that the Tathagata knows to be unfactual,
  untrue, unbeneficial (or: not connected with the goal), unendearing &amp;
  disagreeable to others, he does not say them.</p>
  
  <p>[2] "In the case of words that the Tathagata knows to be factual,
  true, unbeneficial, unendearing &amp; disagreeable to others, he does not
  say them.</p>
  
  <p>[3] "<strong>In the case of words that the Tathagata knows to be <strike>factual,
  true,</strike> beneficial, but unendearing &amp; disagreeable to others, <em>he has a
  sense of the proper time</em> for saying them.</strong></p>
  
  <p>[4] "In the case of words that the Tathagata knows to be unfactual,
  untrue, unbeneficial, but endearing &amp; agreeable to others, he does not
  say them.</p>
  
  <p>[5] "In the case of words that the Tathagata knows to be factual,
  true, unbeneficial, but endearing &amp; agreeable to others, he does not
  say them.</p>
  
  <p>[6] "In the case of words that the Tathagata knows to be factual,
  true, beneficial, and endearing &amp; agreeable to others, he has a sense
  of the proper time for saying them. Why is that? Because the Tathagata
  has sympathy for living beings."</p>
</blockquote>
 -1: <p>First off, I think it's important to understand that Zen isn't something that should be greased up and crammed into the strictures of traditional Buddhist teachings.  Zen makes no overt attempt to follow the path as laid out in the Sutta Pitaka (i.e. in the Samanaphala Sutta) nor does it conform to the gradual training as described in texts like the Vissuddhimagga.  Topics like right action, sila, and virtue, while undoubtedly present in the Zen tradition, are meant to be arrived at through direct insight.  They are realities to be discovered, not guidelines to be followed during the initial stages of practice.   </p>

<p>The particular quotes that you are referring to are from two koans.  Specifically, they come from cases 1 and 21 from the koan collection entitled the Mumokan.  In Zen practice, koans are designed to point at some subtle experience of reality (i.e. big mind) that is often missed by our discursive and discriminating smaller minds.  They are not designed to be "thought provoking", nor do they try to be necessarily humorous, provoke anger, or instill discomfort.  They don't even try to cause dissonance.  For these reasons, they can often sound completely nonsensical.  In fact, koans are "none-sense" in the purest definition of the word.  No amount of reasoning will help you arrive at the experience they are pointing to.</p>

<p>That being said, koans are surgically precise.  They aren't just "right speech" they are "exact speech".  The experiences that a koan points to are ridiculously specific and, in the hands of a master teacher, can be used to great affect in awakening a student.  A good teacher knows exactly when to introduce a certain koan.  Like someone playing a game of Jenga, he knows just what block to pull out in order to get a student's whole mental edifice to come toppling down.  </p>

<p>All koans seek to awaken the mind.   Not a single word of them is tossed off haphazardly.  They are skillful means - upaya - but are functionally quite distinct from anything you might find in the Theravadan tradition.     </p>
