I would say that ESL teachers can be knowledgeable and be gifted with the power of teaching, but can fail very badly on pronunciation, word meanings, and constructing colloquialismswhich are in very general use. As an ESL qualified teacher I have trawled a lot of teaching websites and seen a lot of introductory videos made by online ESL teachers. It's just fact that Filipinos are often the worst. I love Pinoy, the most polite, cheerful and hardworking people I generally meet. The UAE leisure and hospitality sectors would be in deep trouble without them! My comment is purely based on observation.