If setup a script to let google-adbots see your "google landing page" IE the one that will have a high relevancy score thus low cost per click and then redirect real users to your affiliate page how do they know ? I can't imagine they review every single freaking ad created in adwords by hand. I setup a sample domain - started a ad - had a script that let the nice SEO page be seen by only google bots - ad-bots etc and still within 2 hours the ads were taken off because the "destination URL does not exist". I checked my logs - all the bots saw was the SEO page but they still found out somehow that real users were getting sent to affiliate page - or at least were not seeing the SEO page. Would love to know how they found out.
Ya I added that one I found on the net that was disguised- but I had 0 clicks the ads were only 2 hours old - and my logs only showed the google-bot and the ctk or whatever it is called in the page I set up for the bots. no hits to the SEO page for real users.
They have started manual checks, especially checking whether the visible URL matches the destination. I've had to add so many random IP ranges (many from India, Canada, and a few from the US) to the list of Google IPs I currently send to a landing page in order to get some of my campaigns back online.