Actually since both Google and Yahoo want to make money from PPC advertisers, they accept most ads if the AD appears generally OK and if at all there's any problem, wait for someone to complain to investigate.
I believe that the Support staff at both Google and Yahoo do not possess indepth knowledge about online marketing tactics and that is the reason why many can get away with ADs that rip-off original stakeholders. The most frustrating part is that everytime you call customer support you speak to a tom, dick or harry and have to repeat the entire story
again and again...
JG