Ah well, this is what makes the world go round - variety. Everyone has his own p.o.v. *Mine* is that "gotten" is the worst word going. It depends where you are from I suppose. Americans use "gotten" and can 'get' away with it. I am not American.
I would "correct" your example sentence below with:
"They should have *hired* a better teacher".
I don't really see how the first sentence is bad and the second one isn't.

> I agree we should teach good English. But the word 'gotten' is not
> bad English. Yes, he's got a skateboard is not good English, but they
> should have gotten a teacher is not bad English - even though a
> better word could have been chosen. Just need to be careful that we
> distinguish between correct English, "better" English, and
> incorrect English.