I have asked a similar question over on StackOverflow about this practice, and the general consensus is that answering bad questions is a frowned upon practice.
To explain; when a bad question is asked that is quite clearly off topic, or unclear, it should not be answered - only closed.
The idea is that once a bad question is answered, and the answer is upvoted, that question will remain forevermore, be of no use to anyone, and generally degrade the overall quality of the site. It makes sense.
Should/Is the same ideal practiced here? It's fairly understandable on StackOverflow, they require heavy moderation considering the sheer amount of questions they get per day. However on other sites (for example, here) I have noticed that it is a bit less direct.
So how do we identify and deal with questions that should be closed and not answered?