Assume that when an editor makes an edit, it was to help the wiki, not to vandalise it. Since anyone can edit, we must assume that most people who work on the wiki are trying to help it, not hurt it. If you are positive someone made a nonconstructive edit, then feel free to correct it. When disagreeing with people, remember that they are probably thinking they are helping the wiki. Consider using talk pages to explain yourself and give others opportunity to do the same. This can avoid problems and prevent them from escalating.