I often "claim" my downvotes (aka I will post "downvoted" and then give reason.) However, I know that when I do this, I will be downvoted myself. So that is probably one big deterrent to others doing the same.

On the other hand if people agree with your reasons they often upvote it (especially back up towards zero if it dropped negative).

For one thing, the person you are downvoting will generally retaliate by downvoting you (or so it seems to me, since I tend to get an instant -1 on downvoting comments)

I certainly hope so. I would expect that they disagree with your reasons for downvoting or else they would have not made their comment. It would take a particularly insightful explanation for your vote for them to believe that you influencing others toward thinking their contribution is negative is itself a valuable contribution.

Also, many people on this site are just a-holes. Sorry.

*arch*