It seems to me in reading the posts the simple way for google to do this is to simply scan a proposed ad to see if the destination URL is already being advertised for the key words purposed. If so does the new ad have a higher bid? If yes the new ad shows, and the old one disappears. (That is essentially an auction) That way it is still automated, still based on relevancy (a more relevant ad means it costs less for a top bid) and there would be no favoritism shown to a merchant, agency or affiliate. Not a bad system, and one I could live with if it comes down this way. For those of you purposing to create simple doorway pages it won’t work. You will get slaughtered because of your dramatic decrease in conversions. Take my advice if it happens take you best ads, buy a domain for each ad, and work on creating a value added experience for the end user on your site and you might be surprised that you end making even more money by creating added value. It also gives you more leverage over your merchants if you advertise more than one merchant.