Folks are not going to vote for a man they don't trust
This is the point so many talking-heads fail to grasp. There is such a thing as being too well-prepared. Any polished speaker can win a debate, merely by being better able to recite a list of factoids from memory. I would concede that Bush lost the first debate if only because he did not go after Kerry on his vote on the first Gulf War and because Bush seemed tired. But his answers were more truthful and consistent (perhaps too consistent in that they seemed repetitive).