well... it comes to mind that if someone really *wanted* to, there are a bunch of ways they could rip you off, in the same way a sponsor would rip an affiliate.

Send sales to an alternate processor when traffic is arriving from certain regions, set up an alternate merchant account and siphon a small portion of traffic to that, assign a portion of direct sales to a nonexistent affiliate, etc.

I guess my feeling is that if you don't completely trust the person you're doing the deal with, you shouldn't do it.