My theory on ads is that short of Swift Vets, you can't really put an image in people's minds. You can make an image that's already there better or worse.
For example, the DNC can run an ad on Bush saying we can't win the war on terror and then show him saying we are winning and will win it. But people aren't going to care, because no one doesn't understand Bush's position on the war.
Works the same with jokes. There has to be the tiniest bit of truth or it's not funny. Jokes about Mother Theresa being a serial killer aren't funny, for example.
