Recently I encountered a question on one of the Stack Exchange sites that had a comment below that said something like
Downvoters should comment so the question can be improved
It was a comment by a moderator for a question at -1 that seemed reasonably well-researched and clear. I have even seen things like
Please refrain from downvoting bad questions that are salvageable if they are below -1.
in comments as well. It seems like the norms are not consistent across Stack Exchange sites. One moderator at a particular site has specifically said that such comments are inappropriate while other sites' mods are actually the ones making such comments! I think that when a moderator makes such posts it sends mixed signals as to whether these sorts of comments are appropriate, even though most of the Meta community views them as inappropriate.
Obviously people are free to vote as they choose and we should not "force" people to explain their votes. It is definitely important that voting be completely anonymous if the voter would like to remain anonymous (there is clear consensus on this amongst many posts on the meta). However, I have not seen any post on the meta that says it is inappropriate for a user to leave a comment suggesting down-voters give feedback and that such a post should be deleted. Although, the majority of users seem to think such comments are not constructive. -- Edit: As of 2018 the majority of users consider these comments constructive
I am mainly asking this question for guidance as to whether such comments should be flagged or not, since there is nothing in SE policy that says they should or shouldn't (and there is also no meta SE post that explicitly states this either). It is only fair that users be able to have at least some idea as to why their comment gets deleted. I hope that an answer to this post can serve such a purpose.