The thing is there are tons of native speaking Chinese that take AP Chinese and SAT subj tests to dress up their credentials. To them, they can close their eyes to get 5 or 800 on the subject. As a result, if you cannot get 100% from taking them, you mind as well not to take it.
I was told about this by a kid I know who has graduated from Berkeley already, there is no gain for him to tell me that.