"Dentist"? What does a dentist have to do with this? And a phantom one at that.
That MUST be a clue of some sorts. It doesn't fit with anything I've said before about possible scum groups, but if I follow the Discworld shtick of perverting fantasy tropes, I would personally guess a serial killer. (As in: the horror trope of a dentist with drills, etc.) As we all know, Isaac is always the first one to come up with the possibility of an SK when discussing the possible scum factions, so it stands to reason he will put one in his game.
Not sure about the phantom part, though. Maybe this is what "unseen"/invisible (as in the unseen ram-tip) refers to?
That would make all the other things (skills, pamphlets, RPS) red herrings.