The OP implies that a (perhaps the) scum faction is Aogiri Tree. CCG could also be Scum as well, as Anteiku seems to be Town. So we might have two Scum factions. However we aren't allowed to flavour claim, so I think trying to figure out the game based on flavour is not informative and ultimately just a distraction. The Tokyo Ghoul theme is there to make being a host more enjoyable for @Noctis, and appears to be all there is to it in this game. With flavour claims resulting in Mod Kills we can't really infer the set up from the flavour except by watching the flips of those that die.
I agree that there are at least 4 Scum in the game.