I'm an American. I was born in Spain, but raised in the states (and I'm a legal american citizen). At present, I'm living in southern Spain and work as an
ESL teacher.
I find that other than accent, which people don't really mind
too much about, most teacher here are worried about vocabulary. There are many words that differ between BE and AE, and other teachers here have a very hard time accepting AE words, specially when there's another way to say it in BE, such as balaclava, for ski mask... I'm the only AE speaker in my school, and always speak up, but my point of view is never accepted. I have recently started a vocabulary list with the differences between Be and AE so that the students can be aware of what's going on.