Sounds like it would be a great way for Google to experiment with crowdsourcing results quality. If there's a ton of people blocking, say, experts-exchange.com

Sounds like it would be a great way for Google to experiment with crowdsourcing results quality. If there's a ton of people blocking, say, experts-exchange.com – that should feedback into their search result quality ranking. Of course scammers would attempt to game this system too (by, for example, blacklisting stackoverflow.com) :)