@Setanta,
You beat me to the punch, Setanta.
Out of fairness to Americans, I was just about to declare that people from my own country can be an embarrassment, too.
When I used to travel a lot more, I used to avoid Kuta (Bali) for that very reason. It was (probably still is) full of Australians behaving badly. Horrible.
But hey, to be fair to everyone, I don't think bad behavior in public is necessarily the characteristic of the citizens of
any particular country, really .... it's just that you cringe a whole lot more when they are from your own.
The most embarrassing moment I can recall, off the top of my head: standing in a ticket que at a railway station in Amsterdam quite a few years ago, I struck up a conversation with the woman who was standing behind me. Who turned out to be an America & who turned out to be very LOUD. After declaring that Europe was a real let-down, not half as interesting as she'd expected & that she couldn't wait to go home ..... she declared extra loudly, "This city is so DIRTY!"
Agh.
It was kind of mortifying to be associated with her in any way.