Sometimes a question is asked, and an answer is given which directly addresses the question. Then the question is edited in a way that changes what is being asked (as opposed to spelling/grammar, adding a link etc.). What ends up happening is that it reflects poorly on the one who answered, because to anyone who isn't aware of the question's history, it looks like the answer does not address the question.
I've noticed this before, and it happened to me today here. Basically I gave the basis for a particular stance of Orthodoxy, because the questioner asked for the basis. Then the questioner realized that the basis was not what he was looking for, so he changed the question (with the aid of others) to ask for the philosophical justification instead. I feel like this makes me look a bit like a troll now, to anyone who doesn't bother to logically derive from the comments that the questioner had once asked for the basis.
My suggestion is simple: Once a question is answered, no edits that change the meaning of the question should be allowed. If it is determined that the question as it is is off-topic or a duplicate, it should be closed, not changed. The questioner, of course, always has the option to ask another question, so no one loses.