Unless the teacher was abusive, sarcastic or nasty, I think I would at least try to put my Big Girl Panties on and learn from these ladies. At least for the duration of the class... The level of their standards may be new to your sister, but if she puts aside her offense and listens and applies their "perfectionism" she could learn a lot. It may even help her bypass some of the bad habits that she might have otherwise developed.
Teachers are just people-- all different kinds. You will find some you relate to a lot better than others, but you can usually learn something from all of them.