Today there was this question: Which scales are used by Tom Morello?
I really like this question, but I have a feeling that this wouldn't really be of any help to future readers.
So is this question off topic?
I do think the question is on topic. It often lies in a musical performers interest to incorporate other players styles in his/hers playing. Getting knowledgeable people to discuss or analyze that player's style is helpful, and if the player is known enough there will be general interest. As the answer to the question shows, I think it is clear that interesting things has already been obtained from this question.
I think we should give questions the benefit of the doubt in general, since we are not drowning in questions. Some questions are clearly of limited use, but I feel there is a tendency to be too worried about what's on topic, rather than gaining momentum and avoiding scaring people off. (I myself has been guilty of this...)
I think Morello is influential enough and innovative enough to study, although the specific question asked might be too limited in scope. But then the first answer given to it suggests that even the limited scope of Morello's scale and chord choices may be interesting to performers and composers.
Thus, while I can easily imagine poor questions of this nature, I don't think this question is a poor one, and I've upvoted it. (That said, I think it would be an even better question if it focused on what Morello’s choices accomplish, or why he made them, rather than simply which scales they are.)
I lean towards it being off-topic. I don't see much to distinguish it from any other identification question. And the answer is probably "a whole freakin' lot".
You could argue that Morello is popular enough for the question to have some use to visitors, but I would argue back that it is essentially static, uneducational information. As a site for musicians and not listeners, we want to help people improve their musical skills. Asking how to identify scales fits this model; asking someone else to do it for you does not.