Furthermore, there will always be a delay before an answer can be corrected - during that delay people could read the wrong answer, and take it to be correct.
repost it somewhere else (maybe even here) as the "correct" answer.
I've seen bad memes that refuse to die, posted again and again in response to the same FAQs.
I'd prefer it if someone posts "this isn't tested", or "I saw this answer but there may be better ones" if that is indeed true. Even I still answer that way on the areas in which I'm not a firsthand expert.
Over time, people can sometimes assess "This person doesn't really know as much about this particular subject as he/she thinks they do", but that's hard to pick out in the beginning, especially if they talk big.
There's a particular troll in the newsgroups who is like this, leading the true beginners astray. Luckily, the experts haven't entirely given up putting prophylactic postings around the troll's answers.
-- Randal L. Schwartz, Perl hacker