At Search Engine Roundtable, I wrote Google AdWords Ridding Themselves of Affiliates, which documents a case of a long time AdWords advertiser saying he was told by his Google representative that he and his kind are no longer wanted in the AdWords program. This all goes back to the new quality score for landing pages, which tend to weed out affiliate sites. Basically, the "quality" of affiliate sites are not high enough anymore to do well in the new quality score algorithm. Google may be weeding out these affiliates by inflating their minimum bid to prices that are not economically sound for them. From the post:
When I asked what I could do to make it meet their new guidelines she told me, "Honestly we have not had any good news for these types of sites." No help offered.