Is it acceptable to edit in "This answer is wrong" header into a wrong but upvoted answer?

Question

Thanks to Yet Another Hot Question List Ignorance Incident, we have a question with an answer that is 100% wrong and contradicted by canon, yet upvoted to 50+ upvotes.

So far, I posted a correct answer, asked the OP to consider changing their "Accept", and posted a comment under an incorrect answer.

However, (barring the OP changing their accept mark), that seems well-nigh useless: nobody will read a comment under a long answer with 50+ upvotes to check if that answer is correct; and nobody will pay any attention to an answer with a couple of upvotes when the accepted one has 50+. And the "normal" self-correction mechanism of SE site won't work here, since there will be no flood of ~4000 viewers to provide enough upvotes for the correct answer to even remotely catch up, even in several years.

Would it be an acceptable thing, to edit in a disclaimer note at the START of the answer, that the answer is canonically wrong, and opposite of what the correct answer is?

Answer 1

No. Adding a note to their answer saying "THIS IS WRONG, SEE MY ANSWER BELOW" would be a form of vandalism.

The correct procedure is to add a comment explaining why the answer is wrong. The answer will then be (gradually) outvoted by your correct answer. It might take years but them's is the downside of a vote-based system.

You might also want to address a note to the poster (who seems to be a regular visitor) explaining why their answer is wrong and encouraging them to delete or amend their previous answer with the correct canon information.

Answer 2

No.

Commenting and voting are the tools we have for “correcting” the balance if an answer is incorrect. Inserting chunks of text into other people’s post because you don’t like their answer is an abuse of editing privileges, as well as being just plain rude. Is it unfortunate that an answer is “incorrect”? Perhaps, but not enough to justify vandalising somebody’s answer.

I’d reject such an edit if I saw it in the Suggested Edits queue, and revert it if it was actually applied to a post.

Answer 3

I agree with Alexwlchan and Richard. The nice thing to do, the thing that would most encourage community building, in my opinion, is to either try and salvage the answer in the most minimalist way possible, or to work with the answering party on correcting his/her errors until he/she has a quality answer. It's okay to not always be in a competitive role -- helping someone else to construct a great answer can also be rewarding. But I digress. Anyhow, YMMV, but I wouldn't mind being the recipient of this approach.

Moving on, no, for the love of Pete, it's totally not okay to edit in "THIS ANSWER IS 100% WRONG -- PLEASE SEE MY ANSWER FOR THE CORRECT ANSWER!" Even if it's true and the answer is terrible, I agree that doing something like this constitutes editorial vandalism. As well, it's poor form and only serves to make the complainant seem vindictive, jealous, or like a pandering rep w***e. There is just no way a person can do this without looking like a huge cad.

This particular situation is going to occasionally happen and I think, aside from my first suggestion of editing the post within reason or offering to help the person who answered fix his/her facts, there is not much to be done about a wrong answer that the OP selects as correct.