[tbp]

It depends on what your policy is for affiliates using PPC. Some merchants will not allow any bidding on their name / brand names, whereas others don't mind.

In the end, you are getting sales, which is the main thing.

The only time that it really causes problems for merchants is when they are using PPC themselves, and then you end up competing with affiliates on your own name. If your not using PPC, then I can't really see its a problem affiliates bidding on your name.