My personal preference for checking out fraudsters is the Bad Budo and Baffling Budo sections of E-Budo.com. A lot of the Instructors who post here on Aikiweb are also signed on there and like Aikiweb, one must show their real name when posting. I've also found that E-Budo folks carry a wealth and breadth of knowledge experience well outside the art of Aikido alone, which can give some alternative perspectives on things.
As far as stopping or thwarting fraudulent claims in Aikido goes, I've had to deal with some of that here, where the general awareness of Aikido is small among martial artists and pretty nonexistent outside that sphere. Because this is a small country, what we've been doing is trying to make ourselves more visible to the public so that what they know who we are and what we are doing and also give them an idea of what Aikido is supposed to look like. We also give general guidelines regarding the questions one should ask when visiting a dojo that claims to teach any martial art, especially Aikido.
I have come face to face with Aikido fraudsters here and when they meet me they often quickly change their story in a myriad of ways while in my presence (like claiming to teach some unknown school of Aikijutsu), so pinning them down is a bit difficult. I think the best way to fight misinformation in this case is to flood the environment with a lot more correct information and hope that those who really need that information listen to what is correct, or at least question things before deciding to train with these groups. The thing is, those who have nothing to hide will welcome pointed questions on things like lineage, training methods, affiliations etc.
Just my 2 cents.