I agree with you completely in the difficulty of being certain that a computer is clean once infected, but some people (a la http://xkcd.com/694/ http://xkcd.co

I agree with you completely in the difficulty of being certain that a computer is clean once infected, but some people (a la http://xkcd.com/694/ http://xkcd.com/694/ ) are not willing to deal with "starting from scratch" because it means having to backup their data, reinstall all of their applications, and redo their application settings.