The Core

http://finance.yahoo.com/news/man-furious-google-taking-hundreds-101800563.html

Historically, Google has tried to get bad actors out of its high-quality ad publishing system. Some of these publishers may have used bot traffic or placed ads in a way that "forces" users to click on them. The company has longstanding bans on such publishers. It makes sense for Google to root out websites with poor quality inventory and scraped content, and advertisers like it when Google refunds money that was spent on low-quality clicks.