Obama is leading in all polls but one, which is considered an outlier, and has leads in a number of swing states (though within MoE). Yes, there are dumb people who won't for him because he's black. But that's not the prevailing issue, and it hasn't been yet.
Spears and Hilton are people famous for being famous, not for having any defining talent. That's the nicest semiotic reading of the use of those two. Since one is considered nuts at best, and the latter achieved her fame for being in a porno, again, it's problematic. That they are two promiscious white women may have not been the intention to suggest that Obama wants to know where the white women are at, but surely that was part of the appeal. I guess there aren't similar-level famous himbos.
The problem is that McCain's argument, especially coming from the party of Reagan, and from a man married to an heiress who - outside of the military service - is as far from working class as they come, and has been for a very, very long time.