Q:

How to prevent negative comments/downvoted being deleted by re-posting answers

I recently downvoted an answer on SO because I believe it didn't actually answer the question, and before I could add a comment, the answer had been deleted. Two minutes later, I looked at the question again, and the same user had re-posted his answer, without the downvote.
I've seen this guy remove answers with negative feedback/downvotes in the past and repost them exactly as they were. My biggest concern is that by getting round the system this way will hide legitimate feedback that may be very relevant to whoever asked the original question.
I feel there's an argument for requiring a vote to close ANY answer or question with any kind of feedback. Personally, I've only ever deleted one question that had answers, because I realised there wasn't an easy way to explain what I was asking, and realised shortly after I posted it that it wasn't possible anyway.

A:

While it's OK to do this in isolated incidents, if you notice a pattern of this behavior, that's more serious.
I recommend flagging the relevant posts for moderator attention, with a hyperlink to this meta question URL.

A:

I think probably the correct thing to do here is just appropriately apply your downvote again.  I think this is an edge case, I don't recall ever seeing a user delete and repost just to lose the downvotes.  You could try flagging for moderator attention and explaining the issue, but I'm not sure what the mods would do about it. 
Is it really worth inconveniencing those users who genuinely want to hide their shame tidy the thread by deleting a poor answer that's garnered downvotes?  I certainly wouldn't want to have to wait for others to also vote to delete my answer just because my brain wasn't functioning correctly when I was writing it.

A:

I just ran some stats.
In general people do not delete and repost the same answer, I'm counting a total of 604 incidents in all of SOs life. 
To top this, in general people do not delete and repost on the same question, I'm counting about 5000 times that this happened. 
Of the 604 incidents the top offender only did this 4 or so times, from a look through the actual answers the reasons are fairly varied. 

Some people did not discover the undelete button, its total repost (no comments on the answer) 
Some people wanted to unwikify their answers, so they deleted and reposted a non-wiki version 
Most people did not appear to be deleting and reposting just to get rid of comments. 

I guess the reason why this is so rare, is cause people with more than 10k rep can just look, see if something fishy is going on and flag. 
Personally, I do not think any changes need to be made, delete does not purge info from the system, if its totally valid it can be reposted by high rep users or undeleted. 
Comments are just, hmmm comments. Rule of thumb, if a question / answer loses significant value as a result of deleting a comment, the comment should not have been a comment. 

What should you do if you notice a
  repeat offense ???

Just flag it, the mods will have a look. 

