I remember that banner ads network before has a black list containing publishers booted out for fraud that they share among each other. I would think that this is something that contextual ad networks would also develop, if they haven't already done so.
Even though I have nothing to fear, I still like to know I have a backup plan. I tested most of the popular programs and none of them near adsense, except maybe for AdSonar. But it can happen to most "experienced" publisher.
But if you're a little scammer, then it's most likely that you'll get suspended on yahoo as well. Especially take in consideration that Yahoo uses human editors.