I think it'd be a good idea (if it doesn't already exist) to have a forum or stickied thread for reporting scammers. Sure you can just report someone by the helpdesk, but even at that, they can still continue to scam others. It could contain things such as the scammer's url, account name for billing systems as such.
Often scammers will use the same screenshots of their billing system over and over again to scam others; so the URL / username would remain the same. Just recently I received an email from [email protected] offering to sell his clients. I went on lixs.net and tried to register an account there. Sure enough, the invoice returned as #1 overall invoice. He also provided a few screenshots of his billing system with the username of "Numo". I did a google search of "Numo whmcs" and the first link was this one. I think it'd be a lot easier to have a thread you could just look through for this type of information.