From The Editors, the best explanation of Bush’s shoe-dodging I’ve yet seen:

Judged as a display of alertness and ninja prowess, the President’s dodge is, indeed, impressive.  But George W. Bush has spent most of his life fucking things up horribly, and then escaping any consequences for his incompetence and indifference.  This is who he is.  What you have seen is not a moment of quick thinking, it was  the man’s essence.  He always escapes unharmed.