English Majors or English professionals don't approve simple people teaching english, why?

Why is it English majors or people with perfect english grammar are full of themselves, and think that i shouldn't teach english to foreigners? I know i have bad grammar, and i have an accent(i'm hispanic american) but i have good teaching techniques, i make it fun, and in fact i've taught several japanese and chinese people and they are really happy that i help them. i also speak japanese so i can explain concepts to some of them. Whats wrong with teaching even if i'm not perfect...Some people in yahoo answers think that to teach i should have perfect american accent, have perfect grammar, and be talkativve outgoing like many new yorkers i see in tv. but i feel i can teach even if i m not like that