Part of the problem in the US is the same problem we have in the UK.
'Hmmm.. Should I treat this wound with Hydrochloric Acid or Arsenic?'
None of the choices are really acceptable, there's such a massive gulf between the political view of reality and the view from ground level that the two are very rarely headed in the same direction.
Certainly, in the US, the political agenda is no longer controlled by the people to a massive degree, politics is about pleasing the Corporations, and then the corps use Media to influece the people.
In the UK, it's very press-centric, our government seem to think that the News makes the Papers, and still haven't figured out that the opposite is true, so now rags like the Sun are dictating governmental policy to the ministers as their own opinions see fit, this has caused more than a few problems.
So, are American's stupid? I don't think they are particularly more stupid than any other race,, but when we vote in an idiot nowadays, it only mostly impacts us (unless Blair starts handing out our army for loans), whereas the US having an idiot in charge has a much more noticeable impact on other countries. It's this, I think, that makes people more aware of when the US has an idiot in charge.