There's really no telling of people's characters. Those things never fail to amaze me. You think you knew someone and there they go, turning out to be completely different.
And why, oh why, must it be a disappointing experience most of the time?
That's why I believe that being a teacher is one of the few fully-rewarding jobs there are. Well, at least from my point of view.
When you see the will to learn and overcome their trouble these kids have... Man.