user12365: 
Helpful: Is an idea of being helpful, such an intent, a secure attribut of skilful action?
Can intention of being helpful be very unskilful? Thinking on mercy-killing, or taking away dirt, which in unknowenly actually the food of the person one thought to help.
What is helpful? What might be right resolve, intent, leading a helpful and skilful act?
Does a helpful act always benefits both, or just one of giver and receiver, or how should it be understood?

An illustration might be helpful: The compassioned monkey.
[Note: This is a gift of Dhamma and not meant for commercial purpose or other low wordily gains by means of trade and exchange.]

user-1: 
Can intention of being helpful be very unskilful?

Yes, if the intention is based in one of the three unwholesome roots; greed, hatred, delusion.

Does a helpful act always benefits both, or just one of giver and receiver, or how should it be understood?

Regarding the giving of food, the Buddha taught that its beneficial for both giver and reciever.
In the Suppavāsā Sutta (the Gift of Food), the Buddha gave the following teaching to the Koliyan Lady Suppavāsā;

"Suppavāsā, a noble female disciple, by giving food, gives four
  things to those who receive it. What four? She gives long life, beauty,
  happiness, and strength. By giving long life, she herself will be
  endowed with long life, human or divine. By giving beauty, she herself
  will be endowed with beauty, human or divine. By giving happiness,
  she herself will be endowed with happiness, human or divine. By giving
  strength, she herself will be endowed with strength, human or
  divine. A noble female disciple, by giving food, gives those four things
  to those who receive it".
-- AN 4:57; II 62–63, Bodhi trans


12365: <ul>
<li><p>Helpful: Is an idea of being helpful, such an intent, a secure attribut of skilful action?</p></li>
<li><p>Can intention of being helpful be very unskilful? Thinking on mercy-killing, or taking away dirt, which in unknowenly actually the food of the person one thought to help.</p></li>
<li><p>What is helpful? What might be right resolve, intent, leading a helpful and skilful act?</p></li>
<li><p>Does a helpful act always benefits both, or just one of giver and receiver, or how should it be understood?</p></li>
</ul>

<p>An illustration might be helpful: <a href="http://sangham.net/index.php/topic,806.msg2492.html#msg2492" rel="nofollow noreferrer">The compassioned monkey.</a></p>

<p><em>[Note: This is a gift of Dhamma and not meant for commercial purpose or other low wordily gains by means of trade and exchange.]</em></p>
 -1: <blockquote>
  <p>Can intention of being helpful be very unskilful?</p>
</blockquote>

<p>Yes, if the intention is based in one of the <a href="https://en.wikipedia.org/wiki/Three_poisons" rel="nofollow noreferrer"><em>three unwholesome roots</em></a>; <em>greed, hatred, delusion</em>.</p>

<blockquote>
  <p>Does a helpful act always benefits both, or just one of giver and receiver, or how should it be understood?</p>
</blockquote>

<p>Regarding the giving of food, the Buddha taught that its beneficial for both giver and reciever.</p>

<p>In the Suppavāsā Sutta (the Gift of Food), the Buddha gave the following teaching to the Koliyan Lady Suppavāsā;</p>

<blockquote>
  <p><em>"Suppavāsā, a noble female disciple, by giving food, gives four
  things to those who receive it. What four? She gives long life, beauty,
  happiness, and strength. By giving long life, she herself will be
  endowed with long life, human or divine. By giving beauty, she herself
  will be endowed with beauty, human or divine. By giving happiness,
  she herself will be endowed with happiness, human or divine. By giving
  strength, she herself will be endowed with strength, human or
  divine. A noble female disciple, by giving food, gives those four things
  to those who receive it".</em></p>
  
  <p>-- AN 4:57; II 62–63, Bodhi trans</p>
</blockquote>
