i dont think fake claims are easy because of the role someone lies about. If anything fake claiming becomes hard when you need to think of a name to associate with your role that you think isnt already taken. Due to the sheer size of the supernatural cast, its almost impossible not to fake claim with a name.

Perhaps we look at names and there relevance to the story/flavor and confirmed names (dead people). Anyone with a misplaced or odd name that dosnt suit the flavor is likley lying.