In the end, I think Bush is made of the same kind of Teflon Reagan was. His public persona is likable. People identify with him. He seems like a regular guy. An important part of that is that he goofs up, like the rest of us.
A politician with that kind of persona is just about scandal-proof. People will forgive him for goofing up time and again. All he has to do is say he's sorry, and all is forgiven.
Reagan had it. Clinton had it. JFK had it--remember the Bay of Pigs? Harry Truman had it. Ralph Klein has it in Canada.
Another reason Kerry can't win. This National Guard stuff was going nowhere in the first place.