None-native teachers often have awful accents, and that alone should disqualify. Non-native teachers get all the English upside-down, inside-out, back to front-any-which-way but right; don't they old chum? Those faults should see you applying for a job in the school toilets, hosing it down and not in the classroom. Having said that, such teachers are often paper-qualified, so measure up to what you say a good teacher should have to do a good job