Reviewing proposed edits I've found this one:
I've rejected it as "no improvement whatsoever", but also the question seemed poor quality and I've opened that too. It's closed as too broad, so it shouldn't have been edited just to make it a bit more beautiful.
Should users with low reputation also restricted from editing closed questions (of course everybody should be able to edit his own question)?
I've just realized I've written "old questions" in the last sentence, I've thought "closed questions" as in the title (sorry from them who commented on my request for old questions!).
In addition to my first thoughts; I regularly check reopen votes, they're quite rare, generally done by the question's author, sometimes by somebody else, but I still think that substantially improving a closed question is a tough job if you aren't its author, and quite unlikely a new user will do it.