I think it's fair to say that Parisians of my generation aren't overly fond of Americans. That's too bad, but it doesn't bother me because the truth is that Parisians don't really like anybody. They don't even like other Parisians. Look at the aloof way they behave to each other on the Metro. In that respect they're like New Yorkers. They have to have a reason to like you.
Oddly enough, if you ask Parisians why they don't like Americans there's half a chance they'll say it's because we're rude. One thing they don't like is the way we treat waiters. Yes, you read it right...the way WE treat waiters!!!!
On entering a store or restaurant Parisians always say "Bonjour, monsieur," or "Bonjour, madame" to the first salepeople they lay eyes on. They frequently say goodbye when leaving. No American does that. Where's our manners, the French wonder? They think we were brought up in a barn.
They also don't like the way we eat. From their point of view we wolf food down like there was no tomorrow. Parisians eat slow, cutting the food first then using the knife to steady the food while they carefully spear it with a fork. Even bananas are eaten this way. You never put down the knife til you're finished eating.
Last but not least...I'll just say it without equivocation...they think we pee too much. Not only that, we always expect to use the bathrooms of others, which they'd prefer to keep private. Parisians learn to hold it in from an early age. The older generation used to maintain public pissotierres, which was great, at least for men, but the new generation removed them. You can use a bathroom in a restaurant, but only if you've bought something substantial first. The consensus is that people of breeding don't use other peoples' bathrooms with frequency.
BTW: Some of what I've said here was written up in a book, "The Sweet Life in Paris" by Lebovitz