Today the Trustworthy Accountability Group announced a new pilot blacklist to protect advertisers across the industry. This blacklist comprises data-center IP addresses associated with non-human ad requests. The newly shared blacklist identifies web robots or bots that are being run in data centers but that avoid detection by the IAB/ABC International Spiders & Bots List. In May of 2015 on DoubleClick Campaign Manager alone, we found the blacklist filtered 8.9% of all clicks. Without filtering these clicks from campaign metrics, click-through rates would have been incorrect.”]
Source: https://security.googleblog.com/2015/07/working-together-to-filter-automated.html