I have been traveling to and in Europe and Eastern Europe now for a long time- close to 20 years now and I can count on one hand how many times someone has intentionally been rude to me or us as a couple "just because we were American". I have lost count how many times I have seen traveling Americans be rude, albeit sometimes unintentionally to those serving them.
Americans talk a lot about how people from other countries need to learn English, yet when we travel, the most effort I usually see is a pocket dictionary. The worst is screaming at a waiter, sales person, taxi driver to try to make them understand.
Today we saw the worst kind of American visitor. He pushed past us at the door to get into a busy restaurant ahead of us. He then loudly ordered his food and wine in English. They then proceeded to talk loud enough for the rest of the place to hear, mostly in "leadership" buzzwords and cliches. They competed for the attention of each other, never stopping to breathe and talking constantly over each other. Every time the server approached the table, they ignored her unless they wanted something. As the meal progressed and the wine disappeared from their glasses they just got louder and more competitive. This was a man and a woman who appeared to be new business acquaintances.
It was horrible. It was also kind of like being in a Woody Allen movie. The angst from the man especially was almost visible.
I know first hand how hard it is when you don't speak the language. However I always make an effort and it is always rewarded with kindness. I don't get offended if it's pointed out to me that by now my French, Italian, Polish should be better than it is. They are right.
We are an abrupt culture by nature. Always in a hurry. It's not bad, necessarily- just who we are. If we could just slow down and enjoy a place. You're on vacation in a beautiful place. Enjoy the church you are in before you rush off to photograph the next one. Talk to people about their town, learn a few basic terms, tell them how much you enjoyed your meal.
Even if people can't understand you it's no reason to be rude, shout or ignore them.
So that's my soapbox, born of yet another Ugly American sighting.
Don't be afraid other people in other countries will be rude to you. If you are nice to them and at least try to navigate the language you will be surprised how gracious people really are. They will also make much more of an effort to help you.