It's not just one example, you can 'hurt' a website simply by making a huge list of links with arbritrary query string garbage so that google picks it up, eg:

It's not just one example, you can 'hurt' a website simply by making a huge list of links with arbritrary query string garbage so that google picks it up, eg: http://domain.com/?dupcontent http://domain.com/?dupcontent http://domain.com/?blabla http://domain.com/?blabla What an app should really do is validate the arguments in the query string, remove any invalid ones, then issue a 301 redirect to the proper url. For example: http://www.google.com/search?q=someterm&unknown_variable=nothing http://www.google.com/search?q=someterm&unknown_variable... redirects to http://www.google.com/search?q=someterm http://www.google.com/search?q=someterm Of course that's like getting everyone's CSS to validate correctly :) Edit: It is also why I prefer to sort my query string so that it can be deterministic and always be the same no matter what order the args are in.