Take a look at this question. It's a really crappy question that (especially for the first revision) really deserves its -4 score.
However, one user has written what (to me, who doesn't know jack about Objective C) looks like a great answer, tutorial style.
Knowing nothing about the topic, I can't really judge this or do anything about it, but I just feel bad that the answerer has gone through some lengths to write up a (seemingly) good answer for a question that hardly anybody will ever look at. I can't even upvote the answer, because I don't know if it's good.
One idea that I had was a "Flag for pro attention" kind of thing that make the question show up in some lists for people that are active in the particular tag(s). However, I think things like that have been discussed before, and not really come to a conclusion. I myself can't think of a good way to accomplish this.
But I also don't want to leave this question rotting there. So how would you handle this and similar cases?