Sometimes the stereotypes ring true.My wife (we'd just started dating) was a chaperone for a group of high school seniors on a trip to Paris, Versailles, etc. This was in May of 2003, so anti-Americanism was in full swing. Mostly, though, she noticed that the men wore very tight jeans.
They were on a bus when a nutty Frog verbally abused their principal, accusing him of Judaism and other crimes. He happened to be the principal of a conservative Baptist school, but the poor Frog didn't know this.
In another incident, my wife and some female students were harassed by drunkenly amorous Italians. I suppose most American tourists would have taken them for Frenchmen, so that may be the sort of thing that perpetuates stereotypes.
Also, she ordered butter and got beer. Poor girl.
As for American stereotypes, I was at a 7-11 and asked the Pakistani behind the counter if he had a card I could use to call my girlfriend in France. Some dude in line behind me inquired if my girlfriend was French. I answered that she was not. "Good," he said, "F*** the French."
Good times.