He Has No Rhythm
My brother mentioned it and I realized he was right, and that was one of the things that bothers me about listening to Dubya: his speaking rhythm is wrong. When he speaks he stresses the wrong words in a sentence. He emphasizes the "talking points" which throws off the flow of his speeches. Your subconscious tells you something is wrong, but you're not quite sure what.
It's like listening to a Pole speak Russian: the sounds are there in the proper order, but the stress is on the wrong syllable. It's almost easier to listen to someone who can't quite master the sounds.
When added to the disconnected body language, it's like watching a six-grader tryout for the role of King Lear.