Google now allows 'block sites' on most of Google domains to help users all over the world to take control of their search experience and personalize their results.
In a Inside Search blog post, Johannes Henkel, Search Quality Engineer, cites an explains, "If you're searching on google.fr and come back to the results page after viewing Matt's blog, you'll see an option to block this site."
"You can manage your list of blocked sites from the dashboard, which can be found in your Search Settings. You'll see when you blocked a site and the reason that you did so, and you can unblock sites if you choose," said Henkel.
He said "We've also started incorporating data about sites people have blocked into our general search ranking algorithms to help users find more high quality sites. In the future, we may experiment with data from non-US users' blocked sites,"