Ha, what a great question! You are right on the upvote with the Loud American and the Urban Hiker.
I am going to indulge with a couple of more things on this lovely Saturday afternoon.
First off, many Americans are woefully ill-educated in general as well as about the countries they are going to visit. Their approach when they go abroad (such as your example of the car seat - if I heard correctly- in Madrid) is to look at the locals the same way they look at a giraffe in a zoo. “How cute!” “What a long neck!” “Wow, look at the blue tongue!” Basically they failed to do their homework before leaving, which is to learn about the culture, the customs and the history of a country so that they have an intelligent approach to discovering it in person, which means that they ask a lot of stupid questions and make inane comments that can border on disrespect toward their host country and its inhabitants.
Americans are known for their horrendous table manners. They might want to learn that when you are at a restaurant you don’t eat with your fingers, you hold your fork in the left hand and knife in right hand, and don’t switch over, and you chew with your mouth closed. Above all, pleeeeease don’t blow your nose in your cloth napkin.
Americans need to leave their sense of American Exceptionalism and americanocentric attitude at the departure gate. In most countries, you won’t be served a gallon-size drink filled to the brim with ice cubes, even when it is hot. Get over it. Air conditioning is not standard. If in the United States it is a must due to the flimsy construction methods, in Mediterranean countries, to take an example, you will have thick stone walls, and the buildings (especially the old ones) and their windows will be often be oriented optimally. Beside, a little sweat won’t kill you. Get over it. The laundry is often dried outside. Don’t complain that Downy didn’t make it softer. Get over it.
All in all, Americans abroad are seen as ignorant, entitled, infantile and obnoxious, which is a shame because there are some genuinely good ones in the lot and they get lost in the shuffle.