Right now, people are extremely frustrated and want to point the finger at someone, which is always Bush. However, any person with an IQ over 90 really does understand that people were warned DAYS beforehand to get out and prepare for this, including by the President. They didn't do it. That is not the fault of the President. If the President is to be blamed for anything, it is that he felt the citizens would take the warnings seriously and local and state officials knew how to do their job.
Of course it is not the President's main, only or most important job, but it is the most visible; he is, literally, the face of the government, and in terms of public accountability, the buck stops with him. Fair or unfair, that's the way it is.
It is useful, often, to try to anticipate what the other guys are going to say, and to have a response ready. This is all I am advising the President to do. It is never useful, however, to bury your head in the sand.