Speaking as an American (but not for them) I do believe that most of what you said is true. For the most part, I believe that Americans are politically naive, and that we do in fact eat too much.
And as far as how other countries perceive us... well... I have traveled a great deal and have found that in places that have received very few American tourists, they seem far more hospitable, friendlier, far more eager to talk with us and get to know us, and less annoyed at our presence. I believe the reason for this is, for the most part, other countries have become jaded towards us as a whole. I have seen the reasons for this time and time again... if you take three groups of Americans in a foreign land in a restaurant for example, two of the three will be rude, loud, disrespectful, pushy, and lousy tippers. And that's just in the restaurants. I have seen things of the like happen several places I've been regardless of the circumstances, so I can understand why, over time, the one group out of the three would get overlooked. It really is a shame because I do care about how I am perceived as an American and sadly enough I think that far too few people feel the way I do. It's not so much that they don't care what people think about them, it's that they don't care what other people think.
In reading my letter over again, I find it a bit harsh... Perhaps I myself have become a bit jaded. Know that I do not think that ALL Americans are like this, or even the majority of them, only the majority of the ones that are seen the most.
Feel free to disagree - I welcome opposition, and would like to hear a different perspective.