The Buffy/Angel fandom had a few instances, as well. The Firefly fandom had a whole con(vention) that people paid and flew in for that turned out to *be* a con (job).

There's no way to be sure, so trust and value your friends. You know what's hardest about this kind of thing? It's not anger and embarrassment at being fooled. It's missing the person you thought you knew.