Well, if there are enough people working on a repository, you might be inundated with changes every time you update. You'd never suspect anything unless you knew which files specific users should be editing, and checking that for each patch would probably be prohibitively time consuming.

But unless perforce allows you to delete history, it shouldn't be a big deal to fix. The hard part is finding it. I wonder if there are automated systems that can check the patches users commit and look for "outliers" in content or style?