It's actually a result of googlebombing, not Google themselves at all. A bunch of people linked to Bush's bio with the word "failure" and Google
ranks pages based on how many links they have for that term.
you used to be able to type in "weapons of mass destruction" into google then hit "I'm feeling lucky" it would bring up a spoof 404 html error
page, i've found a link to a copy of it here