I find it difficult to understand how you would even interview & accept a job without understanding what the company did.
Also I would strongly suspect that most traders of stolen goods (ad spots, in this case) would have a path for legitimately acquired merchandise as well, not only for plausible deniability but also because they sure would not mind paying their bills in a clean way, they just failed to resist the lure of the extra cash. With that in place, you'd have to actually work in the shady part to know about it, or have bird's eye numbers of the whole company where you might see that output does not match the legitimate input.