It's not necessarily xenophobic. I remember an organic chemistry class as an undergrad with three TA's, all foreigners. One was Panamanian Chinese - excellent English, one was Chinese Chinese with decent English (strong accent, mistakes, but perfectly functional), and a third Chinese guy with basically no English. The only way of communicating with him was to rely on translators - either Chinese-American students who spoke Mandarin or the other Chinese TA (The Panamanian guy didn't speak any Chinese) We were fine with the first two, but complained amongst our selves constantly about the third - it really isn't too much to ask that ones teachers be able to speak with you.