A hot topic in Affiliate Marketing has been PPC policies of merchants and how their decisions affect their Affiliates.  Many Affiliate Programs allow PPC bidding on their brand.  Some merchants restrict Affiliate bidding to everything but their Trademark.  Affiliate Networks require merchants to set their own PPC Bidding Policies.  Even with policies in place, conflicts between merchant and affiliate over PPC practices are common.

Affiliates have had problems documented where they have made a sale through PPC and had it voided by the merchant, even though no Program Policies were broken.  In this case the merchant realized after the sale that they would like to restrict more PPC actions, and they tried to make a retroactive change.  This is an unethical practice by the merchant and the sale should be allowed.

Affiliates aren’t always innocent.  Merchants can have a clearly defined PPC Bidding Policy, and while checking stats the merchant will see affiliates violating the guidelines.  If this happens you should contact the affiliate, tell them to make necessary changes.  If after multiple contacts and the affiliate hasn’t responded, the affiliate should be cut from the program.

Here is a post by Sean Collins on PPC by Affiliates