Because if I really think about - Obama fits the debonair, perhaps even shady (i.e. Chicacgo) kind of president that ended up in jail and increased his popularity with pseudo-promises of ideals that often wins elections for presidents of the Galaxy in Hitchhiker's Guide to the Galaxy; and McCain is undoubtedly the trigger-happy, showmen (i.e. Palin) who would use a gimmick to boost his odds and then a steal something with guns on it directly after being elected.
Heh, I know I know. I'm waaaaaaaaay off base, right?