I agree. Negative Ads work; but there's more to read into it.
Sure, equating Barack Obama with Paris Hilton has hit home. And sure, people on the face will tell you that they are not swayed, though they actually are. But look more carefully and you will see that in most cases Negative Ads are devastating when its about a real, living person. Associate the negative message with an inanimate object, a product or service brand, the effect though debilitating, may not be as destructive. That's because we are swayed more by what we know about people. Guess why gossip's almost always about someone? Our morbid fascination for the frailties of others may even at times get us to gloat within, though on the outside we'd be excelling at commiserations.
In the case of Barack Obama-Paris Hilton association, the Ad crystallized voters’ opinions without presenting any new information.