Perhaps jailing is the final tactic?
I shall explain my theory.
Jailing tells us that they are innocent. Everyone so far who has gone to jail is innocent.
Now, it is possible this could be true. But you would think that we would have gotten at least one scum/third-party/whatever.
Hospitalization could perhaps after a while, tell us the true faction, role, etc. because of the doctor's checking up on one's background. Maybe jailing doesn't cover that. Perhaps because Wiggum left town, that makes everyone who goes to jail auto-innocent. I'm just theorizing here.
Perhaps what we need to do, is, instead of jailing people, we need to hospitalize them. This will, after a while, let us know their true identities. If we find someone (as we found DaveShack), we then Jail them the next day.
Of course, that may be too slow, and we have just been completely missing our scum. Remember TheBake. We jailed him, and he turned out neutral, which throws a major kink into my above theory.
Anyway, I believe that instead of jailing, we should begin hospitalization. Note how in the tallies, there is also a vote on whether to Jail or Hospitalize.
Those are my thoughts.