Interesting question I got asked last week:
Hey $hoe, I have a question. Why do you think Google continues to allow high ranking spam sites to run Google AdSense? I thought they took a hard stance on this?
If you think about it what would be the most ideal webpage for Google AdSense. The way AdSense works as the publisher, you ONLY make money if someone leaves the website. So a site where you would want to actually retain the user with great content so they want to come back or book mark the site for later use would not be very ideal for Google AdSense.
This is also why you see a lot of SEO’s use Google AdSense as their main form of monetization. They rank for all kinds of terms but yet they don’t really have good content for them. Instead they put up a huge fat Google AdSense square because its more relevant content they have to the search.
Lets be honest it all boils down to money. While the user experience may be shit its super profitable for Google. Last figure I saw said that 90% of Googles income comes from AdSense and of that I would guess a HUGE percentage of that is sites that are purely made for AdSense.
Jason Calacanis said years ago while on a panel with Google AdSense Employees (SES San Jose 06) “I make Google AdSense too much money for them to ban me” in response to a person in the audience asking if he was worried about being banned since he was violating many of Googles Terms Of Service.