If you think it can be salvaged to the point where it's an acceptable question, or if it's borderline, go ahead.
But if it's completely obvious that this is not a good fit for the site (i.e., can be immediately classified as off topic, too localized, etc.), and is not a migration candidate, then the ultimate fate of that question is, or at least should be, deletion.
Editing stuff that's going to be deleted anyway is a waste of your time, because:
it's not going to stick around, so it doesn't need to be pretty; your time is better spent elsewhere
if you suggest an edit, you're wasting the time of the people who review edit suggestions as well, and the +2 rep bonus will be revoked if the post is deleted anyway
the site doesn't give you any recognition for it; edits on deleted posts don't count for badges, for example