I think the thing that has brought Hitler to mind in association with Bush is the very real fear that many people have over what is happening in the United States.
The US is not A world power, it is THE world power. It can do any damn thing it wants, and there is NOBODY to stop it. The US AND the world needs the US to have a good, strong and fair president, now more than any other time in history. The President of the United States affects every citizen of the world far more than our own leaders do, and this is unusual in history.
As a result, it matters a very great deal, and people care a very great deal what happens in the US at election time. I think the people of the world feel highly vulnerable in the face of it, they feel threatened by the enormous power held by this one single man, a man who is not a particularly good or wise man. I think it is very, very natural to vilify something that frightens us so much.