It drives me nuts when people don't read a question, than then respond to it incorrectly. An example: On Programmers, someone asked the etiquette of forking a project. Rather than discussing that, the responses were about how to actually create the fork.
I get down voted for actually answering the question that was asked. Someone else gets up voted for answering the wrong question. That response could have just been "RTFM"...
I also see too many (and google doesn't help with this) unusable answers to questions. I google for "how to xyz", I get "so and so wrote an article on "axu". But it gets up voted, google picks up on it and nobody bothers to actually write a correct answer.
Can't we add a button or something to flag answers like questions are? To me, bad answers seem to be worse than bad questions. If this wasn't the best site, I'd so go to another site.
PS. (off topic) Can we have a programmer ethics question board?