Or someone pointed it out to you and you realize they are right? I'd delete it but I think it would be rude, especially if somebody posted a comment to it already. But then, I don't want the downvotes, too. What would be the ethical thing to do?
I'm not sure if there is a universal answer to this, except "Improve when possible". My approach is:
- I posted a horrible, dangerous answer:
- If it can be amended to fix the gaping holes or problems, do that
- else delete
- I posted a wrong/offtopic answer:
- If it can be amended, do that
- else add a warning note or comment about the misunderstanding if the answer is still useful
- else consider deletion
In hindsight it would often be good to ask the original posters to follow the FAQ on what constitutes a good question, but it would be hypocritical to blame it all on them. Some questions also evolve with the answers, narrowing down on the real issue, so it can be hard to judge which part of the moving target to address.
Downvotes are an integral part of the gamification system, but remember that they hardly affect your reputation.
If there are no meaningful comments, and the time its been up is short (not many people surf away carrying a damaged idea I planted), I delete the answer.
If the mistake has been seen by more than a few and/or informative comments follow, I edit the answer in place, acknowledging the mistake, correcting it if possible. Here's an example: https://gis.stackexchange.com/a/1314/108.
There are probably some other approaches as well. The only unethical move would be, in my opinion, to do nothing at all.
If you're in Italy, you'd better delete your answer, otherwise you might end up in jail.
... the experts had made statements playing down the threat of a repeat of the earthquakes which wrecked the town in 1349, 1461 and 1703, saying the smaller shocks were a "normal geological phenomenon"