Bonzai: "Sometimes it's far quicker just to pull up the plywood too and lay a new subfloor."
Blindly advising someone to "pull up their subfloor" is bad advice on a DIY Internet forum. It doesn't matter whether or not you try to feather your comment by using the word "sometimes". Removing sub-floors is not routine and can effect the structure and get people that don't know any better in a helluva lot of trouble.
Just trying to keeps things as accurate as possible.