RULES GOVERNING THE ENTIRE SITE - BOTH DATING AND FORUMS
(The following rules apply everywhere, where they may be applicable)
No impersonating or libeling anyone - Period. This includes allegations of any sort which use the poster's screen name or real name or other personal information. If you need to report a user - use the Report User feature on their profile.
Misrepresentation and inappropriate behaviour is quite normal, both in the real world and online dating. If the issue is serious enough (eg financial scamming or a threat to your safety), report it to the police, or report his profile to pof, but don't bring it to the forums.