There are one or two users that I have come across who continually and persistently post fake answers. Why do I say fake? Because they always do one of the following:
Give a mathematically completely wrong answer that shows without doubt that he/she knows nothing about the topic! It is not simply mistakes. One very recent example claimed that any property of the domain of a continuous function carries over to the image! Worse still, he/she explicitly said that if the domain is open, the image is too!
Teach others via the comments below their wrong answer! How they have the cheek to do that without knowing what they are talking about I don't know.
Provide a computer program that checks only from 1 to $10^7$ or something, when the question explicitly asks for a proof!
My question is what to do about it. I've tried flagging some such answers in the past but it gave mixed results. Even for reason 3, which is clearly a valid reason (does not answer the question), my flag got rejected TWICE by moderators who apparently don't read comments on flags.
Note that I have on many occasions tried to tell them what is correct and also where their logical errors are, and once in a while some others also do that, but they always instead claim that people are subduing their correct mathematics. So it appears that I cannot stop such nonsense. Why is it that we cannot flag an answer for being wrong and have maybe 5 or so users with higher reputation judge and remove it if it is really wrong? I don't get why we allow non-answers to confuse viewers. I am very tired of downvoting their answers just because they persist on pretending to know things and teaching others complete falsehood.
So this question is not the same as Don't flag wrong answers?, because I don't mind having wrong answers with honest intentions (in fact such answers with their comments could be useful for later readers to understand the mistakes made and also sharpen their understanding), but I don't see any use whatsoever for wrong answers with clearly wrong intentions.