I think there's one thing that makes who's Mafia quite obvious.
Apparently some players are new to this game. I assume that if you're Mafia and you want to win, you'd want to keep as low a profile as possible, only coming up to defend yourself or vote, if you're totally bad at lying. Once again I'm going to reference Sheep, who didn't claim being a Townie or Mafia either.
.. Though I guess the same could be if you're a Townie, so that the Mafia doesn't target you if you're onto them, but at the rate we're going, I think that the Mafia are the quiet ones who we haven't pointed fingers at previously. The people we've been suspecting and lynching (excluding Sheep) so far turned out to be Townies after all.