Eh. Since I post during weird times, I'm usually not in such situations. When I'm posting as anti-town, I do my best to avoid things that I know the absolute truth value to. I can't lie about something that I don't know, so I post about that instead. If you want to catch someone, focus on an issue, and make sure they answer the question. Dodging/ignoring the question is a sign that they've got something to hide.
The other problem with that is when you've got someone that's good enough to make up their own version of things, and remember it to the point where they're convinced it's the truth. It's really hard to pull off, but possible (I did not do this during the last game, nor am I anywhere near good enough to do this).