After reading http://techcrunch.com/2011/02/12/search-still-sucks/ I couldn't help think up a quick fix Google could try, so I'm interested in why this wouldn't work / hasn't been tried yet:

GMail has a 'Report Spam' button, why shouldn't Google search? I'd be happy to log in using my google account before being able to use the spam button, as I'm guessing this would be required to prevent misuse (e.g. has to be reported as spam by n people before affecting a result's rank).

Am I missing something as to why that wouldn't work?