It often surprises me that I run into the same misconceptions about foreigners as the first time I came to Japan 17 years ago.
One is that Japanese people tend to think every Western-looking person is American (or if they don't, they tend to think foreigners are distinguishable by nationality — imagine over 50 identifiable nationalities! Even so, in countries such as the U.S., immigration would have erased any distinguishable national characteristics over 200 years ago).
Japanese people still say to me: "What do you eat for breakfast, bread?" As if we sat down every morning to a large pile of bread on a plate. After so many years of Japanese hotels offering "American Breakfast" with salad, it amazes me that people still see bread as the main component of an American breakfast, without acknowledging eggs, bacon, cereal, fruit, etc.