I can't generalise every American and the most time i spent in the US was a few hours at LAX waiting for a flight to Vancouver but every single American i've ever met is at least 2 of these things; loud, arrogant, fat, overly self important.
To illustrate the fat point, i was at terminal 3 and had to got terminal 5 at LAX (or the other way around, idk) and had no idea which direction is was so i asked one of the workers who was like "Well its around that way but its a bit of a walk. Shuttle comes from there if you wait". I was like, nah i'll just walk. Guy looked at me like i had just said i'd fucked his sister.