Well, one way to get past the problem of "the old code is so bad it will clutter the code review" is to only review the changes (except to consider the rest of the code for its contextual value). That is: don't just open up the file and read through it, picking on everything that looks nasty. Rather, open up the diff of the file against the previous revision, and look at the changes. If there's cruft in the change, then bounce it back to be rewritten. If there's cruft outside the change, then live and let live (until you can get a budget for writing unit tests and rewriting it).
Oh... you are using revision control software of some kind, right? If not, I'm never riding a train again.
Not an editor command: Wq