I don't know Pablo, I know plenty of Filipinos who have lived in the the USA and they don't speak English either. These Filipinos were educated in Filipino schools by non-native English speaking teachers and that has not helped them at all. However, I agree with you that a native-speaker does not a good teacher make. However, even with properly trained teachers, as is the case in China, that does not mean that a person will speak the target language either. You might be a great teacher with proper training, and I give you props for that. However well qualified you are, if I put you head to head with a properly qualified native teacher chances are you will not be as good. In non-native speakers I can see the small mistakes that they make when they speak and write. It is just that they don't know all the nuances of the language. I see Chinese syntax in the things written by Chinese teachers at my school, and they are really good at what they do. Same thing with Filipino teachers. They speak to me in English and then I hear a sentence with a hint of Tagalog and sprinkling of Spanish.