A few notes on the various Lanbril rings in New Pavis and the Big Rubble:
Hole Lords 70 members, with 450 associates, headed by a Priest
Harli’s Men 25 members, with 90 associates, headed by a priest
Knobby’s Nippers 5 members – spinoff of Hole Lords, 100 associates, headed by a priest
Unaffiliated others 50 members, 150 associates – members include the city’s sole Master Thief.
Yes, that means there are some 800 or so people associated with the Lanbril cult, even if the vast majority are only as lay members. That gives you an idea of the size of the whole “criminal class” in New Pavis and the Big Rubble – maybe about 1 in 5 adults has some involvement with smuggling, fencing, theft, protection rackets, street gangs, etc.
So if we think about what sort of activities make up the “criminal class” it is likely fencing of goods (and lets face it, where do you sell something that you took in the Rubble from trolls, humans, or dwarves?), theft of goods (your players took the valuable treasure and kept it in a box? Oh no!), protection rackets (from the street gangs), and general street gang robbery, mugging, and so on.