No idea, but for a long time on the show they've been handing bags of cash to Saul, he takes a cut and they get clean money somehow/somewhere. Doesn't really matter how he does it I suppose.
He doesn't spend lavishly, but he makes himself high profile via prolific advertising, represents a lot of really shady folks, and has deep connections to criminal activity. Its seems like that would catch up to him sooner than later.
Yeah, GB = Gale Boetticher