Having been to France almost every year for the past decade, it is easy to see they generally dislike people not from the continent. Most seem to tolerate my French-speaking family, despite us being British, but I have seen on more than one occasion Americans being thrown out of restaurants, being given the finger by youths and one poor soul even got knocked off his bicycle by a car.
On every such instance, the unfortunate tourists were wearing either a baseball cap, T shirt or shorts emblazoned with the stars and stripes, or a I <3 New York type thing. All other Americans were okay in their fairly generic clothing. Of course, they could have just been Canadians. I can't distinguish accents.
In conclusion:
Judy's tips on how to survive in France
1. Don't excessively show off which country you come from. People will think you are a dick.
2. Learn to speak the bloody language.
3. DO NOT GO INTO A TRADITIONAL FRENCH RESTAURANT AND ASK THEM TO MAKE YOU A TRIPLE HAMBURGER IN ENGLISH VERY LOUDLY. (Yes, I saw this happen.)
4. Much like this board, French people may appear hostile, but be nice and they will accept you. Maybe.
So, back on topic, I blame tourists for France's negative perception of the U.S. Toodle pip.