I wouldn't call myself the most patriotic of folks, but it sometimes confuses me why I get so uptight when people repeatedly bash the US. Sure, it's not perfect and it's got it's fair share of foolishness.. but it's a HUGE country with 300 million people!! Statistically, there's bound to be shenanigans! Again, not sure why I should care..
People bash the United States for a number of reasons; the foremost of which being arrogance.
This is coming from a born-and-raised U.S. citizen living in the U.S. right now. I've traveled abroad many times, been to Italy around 4-5 times over summer breaks and lived in Holland for two years.
The Americans you found living in Europe were generally the rudest around; yes, it is a broad generalization, but it was generally true. The general stereotype of an American in Europe was "fat and arrogant" (just like the French stereotype in America is "rude and pompous", even though it's not really true for the most part).
The fact that the U.S. runs around meddling on other people's affairs doesn't help (I mean, let's be honest, regardless of the situation, very few other countries appreciate it if someone else jumps in the middle of their affairs).
The U.S. is the world power. The dominant nation. Generally, the world power always bosses everyone else around, and nobody likes them because of that (see any other past world power in history, like the Romans).
So, I don't get offended when I see people bash the U.S...but I would hope people would give me the same lenience.
For example, I absolutely hated Paris. It was beautiful, but everyone was rude. I'm not going to stereotype the French; everyone OUTSIDE of Paris were polite, wonderful people, especially in the smaller French towns and rurals.