TO HOLLYWOOD it smacked of desperation. That's why the reaction to a new John McCain ad attempting to portray Barack Obama as a kind of mindless celebrity -- likening him to Paris Hilton and Britney Spears -- drew collective yawns and shrugs of irritation from politically active members of the entertainment industry. "I didn't think McCain could look silly," mused Norman Lear. "But that ad diminishes him and makes him look silly." Just for a start, industry types say the ad is wrong: In the Hollywood lexicon, Obama is not a celebrity. He's a rock star. (Note to McCain strategists:...