Culture shock or language shock?
There are some foreign friends can speak chinese very well and they are confident in their Chinese speaking. When people find that there is someone can speak their mother language, they will have high expectations on it subconsciously.
The fact is they thought they should know what werel you talking about, but they didn't. Because they don't know your countries history and cultural background.
When I was in Vietnam, I didn't speak Vietnamese and my local colleague didn't speak Chinese neither. But when you said something, you would get an active response just like "I see!I know what's your meaning, because it's same here! " So even both of us didn't speak our mother languages and maybe spoke fake English (Asian English), there was no misunderstanding or confusion.
Both Vietnam and China are ancient Oriental farming countries. So these two countries people have similar cultural backgrounds. The method of thinking and aesthetics, values. All them are very different with western people.
I went to the theater to watched Vietnamese local opera. I think it is fantastic. But many western people said it's boring just like Vietnamese buildings. So the theater had to created a new western style Vietnamese opera...That's so FUNNY.