Sometimes (and this holds for all SE sites) I find a question that is quite interesting but it's answers aren't much good.
The previous questioner might have accepted an answer because it appealed to him/her, not necessarily because it was logical.
If I go ahead and ask my question it would be closed as a duplicate. Alternatively I can try putting comments in the previous question asking for further clarifications. But it wouldn't get much attention since the question is already closed. Besides that, discussions using comments are generally discouraged.
So what should one do in such cases to get some good answers?