Generally the moderators have nothing to do with the actual mathematical content of the posts. Their work is when the posts are incorrectly made (e.g. questions in answers, or comments in answers), or when spam is posted. Sometimes when blatantly crankish person is posting (although cranks often spam using sock puppets, and give other reasons for deletion, suspension, and whatnot).
One situation where the moderators should never be involved is when a user is posting a wrong answer. In that case the users should downvote, comment, or even vote to delete in some cases.
However what should happen when a user has accepted an answer which is clearly not an answer to the question posted? For example (that's not a real example, hopefully) if the user has asked a question regarding how is the function $\sin x$ can be approximated by polynomials, and the accepted answer states that $\sin x=\cos(\pi+x)$.
This sort of thing occurs often when a question is closed as a duplicate, or some other reason, and the OP just wants to gain those two points and accepts an answer (either without reading, or without trying to understand).
Question: Should the moderators intervene in a situation where an accepted answer is blatantly wrong? Should they delete the answer?
The reasons why moderators should be involved is that accepted answers cannot be deleted by the OP, and I'm not sure they can be deleted by community members. Moderators can force such deletion.
Of course this should only be after some comments have been pointed out that the answer is completely wrong for the question, and no attempts to correct the answer were made.
I am not suggesting, not even remotely, that the moderators will be referees, judges or graders of mathematical content. I am not suggesting to give the moderators a free hand in deleting accepted answers which are mathematically wrong.
However currently, if I were to flag an accepted answer which is not even wrong -- it doesn't answer the question, there is a reasonable chance that the flag is going to be declined. And that's fine in most cases where the community can "self-correct" and delete the post.
In the case of an accepted answer, however, there is no possibility that users delete the answer (perhaps with the exception of an obvious misuse of spam/offensive flags, which would penalize the answerer by a 100 points of reputation, and would be generally an abuse of the flagging system). Therefore if the community thinks an accepted answer should be deleted, they must seek the help of a moderator.
My intention in this meta thread was to raise this issue, and seek input from both the community and the moderators.