See Wes Pruden's light-hearted disquisition on the phenomenon of "Bush hating." He begins with a dissection of New York Times' bilious opinion columnist Frank Rich.
However, as Pruden points out, hating the President is nothing new. Lincoln was reviled as a baboon, Jackson as a hick, millions unfairly blamed Hoover for the depression, and GOP dislike of FDR was legendary. Who can forget our dismay at boorish Lyndon Johnson showing people his operation scar, or picking up his dog by the ears? And, Pruden reminds us, we didn't so much hate Bill Clinton as be embarrassed to have Bubba as our elected "groper-in-chief."
Recently, hating George W. has provided more-or-less innocent merriment (hat tip to Gilbert and Sullivan's Mikado) to many on the left. These sad souls will need to find alternative entertainment after January, 2009.