I work for WebCentral, which sells this product, and while i dont sell this product directly, i have been in meetings where this is discussed, someone asked this question to the advantate rep, and they were saying it goes on a case by case basis really. Coz there has been numerous cases where a rival company has gone onto google, and clicked their rivals links a whole bunch of times.
However, its a minor thing really, Google AdWords really is the best way to advertise your business, PM me your contact number, and i can get someone to call you to discuss it if you like.