There is a user on StackOverflow called Frank Computer or Frank Developer, currently with 6 user IDs:
He persistently asks questions in the 'informix' area, which is one of my areas of professional expertise. I don't want to leave such questions unanswered, but since he never accepts any answer, nor gives any upvote, it is singularly unrewarding dealing with him.
Is there anything that can be done to persuade him to change his ways?
I don't expect to get large amounts of rep out of this - the subject area is a minority interest area. But - especially when others answer his questions - I would like him to give some recognition that others have helped.
I suspect this is a lost cause and I'll just continue as now, ensuring that there is a decent answer to any of his questions and upvoting anyone else who does bother to answer. But it is irksome, to say the least, that he asks questions but won't participate in the community to the extent of giving that which costs him nothing (indeed, that which gives him rep too - but since he doesn't care about that, it doesn't give him an incentive, it seems).
There are distinct signs of improvement. I don't know if someone contacted him; I suspect so (the timing is a little too much of a coincidence). If so, thank you. It seems to have had the desired effect.
PS: It was a bit hard to choose 'an answer' - and a rather arbitrary choice.