I like to think the majority of Americans are not ignorant. However, the exchange students were shocked to see how oblivious some are to countries outside of the U.S. So I'm going to quickly clear up some misconceptions.
The Capital of Spain is not Espana, Espana is Spanish for Spain. The capital is Madrid.
In Switzerland they do not speak Swiss. They Speak French and German.
Hong Kong is not communist. In fact it is the most capitalistic country in the world. China supposedly granted Hong Kong autonomy for fifty years, but has recently been working to change Hong Kong culture towards the modern "Chinese" culture that is more in line with 1st world countries.
Hong Kong is Chinese, not Japanese. They do not speak Japanese there.
Hong Kong speaks Cantonese. There are two types of Chinese-- Mandarin and Cantonese. Mandarin is the Chinese National language. Most business in HK is conducted in English.
Japanese and Chinese do not sound alike. The languages are totally different. Japanese barrows certain characters from Chinese, but also adds their own.
Ninjas, Sumos, Sushi, and Samuri are Japanese not Chinese.
Tibet is a part of China, but only recently. The "Save Tibet" stickers are there because China took over Tibet and is accused of destroying the national identity and culture, so if someone tells you they are Tibetan replying "Oh! I love Chinese stuff!" sounds really ignorant and offensive.
Some of these things are more basic than others, I don't expect that people will understand that Japanese, Cantonese, and Mandarin are so different or even be aware of Cantonese. However, people really shouldn't call an HK guy a communist when he comes from the most capitalistic country in the world. So hopefully this helps.