Since the release of Panda, there have been, however some sites that slip through, or even change their site so that the Panda misses them. Google responded when they rolled out the international Panda update and let users physically block websites they didn’t want to show up in their search results.
The latest news is the addition of a link underneath the result “Block all example.com results”. This data is sent directly to Google and helps them gather information about what sites need to be banned. Basically Google has hired us to help them find the slips in the algorithm by reporting websites that should be blocked.