The first part of this Native versus Non-Native English Teachers series dealt with the most common arguments of native teachers against non-natives. These complaints are related their language skills- accent, pronunciation, grammar and cultural knowledge.
(See Part 1 here)
On the other hand, non-natives' most common defense are related more on native teachers' view and attitude of ESL teaching. I'm not a native speaker so I don't know what's going on in a native speaker's mind. I can only offer possible explanations why native teachers are perceived in a certain way and why perceptions are not always the reality.