I think looks may matter at the beginning but it only goes so far. Anna Nicole Smith was incredibly good looking, and she had money. But there is no way I'd ever spent two hours with her because she had nothing to offer. My guess would be she knew it too which is why she slept around so much. No guy was ever really going to be interested in her.
Britney Spears, even bald, is a pretty girl but she's got nothing else. She's emotionally, intelligectially, and spiritually dead. I could never image spending anytime with someone that far gone.
For the ladies, and this is just off the top of my head but I assume Tom Cruise is good looking. He's also completely nuts and once he fired his publist who kept his lunitc behavior covered up for years the public really saw he had no substance.
On the flip side, I think I can safely say Howard Stern isn't a good looking man. Yet he has beautiful women willing to do anything for him.
All that being said, I think looks to play a part in life and in attraction, no question. I just don't think they mean anything over the long haul. I think looks might help in the initial stages but at some point you have to have something to back it up. You've got to have some kind of foundation of being.