[Google](http://support.google.com/websearch/bin/answer.py?hl=en&answer=1210386):
>The Blocked Sites feature is no longer available. To block particular sites from your search results, we recommend the Personal Blocklist Chrome extension from Google. You may also download your existing blocked sites list as a text file.
Totally not related to Google’s ability to sell ads. *Totally* different.
See also: [Massive botnet costs advertisers millions, but hackers may not be to blame.](http://www.theverge.com/2013/3/19/4123720/massive-botnet-defrauds-advertisers-millions-shady-origins)