Well, certainly there are "some Americans who despise Chinese people" but not BECAUSE they speak poor English. They rather USE this as a means to degrade and mock Chinese people.
Obviously Chinese and Americans have different cultures, which in some cases lead to hatred. It's merely because lots of people around the world, and not just Americans, don't know our history, don't understand where we Chinese come from and why we behave like we do. The whole world is screaming at us, trying to make us adapt to the western pattern.
Well, we respect your customs, wish you could respect ours!