I have had a similar experience when I took a class with a nationally known instructor (and I paid a bundle for the class). She criticized everything from the way I cut fabric (I use the double ruler method or the Shape Cut and she hated both) to the fact that I have hand and arm problems and have to accommodate that both in cutting and sewing - she did not make suggestions, her comments were along the line if you don't do things exactly the way I tell you, then you are a failure and should leave. I took the class because she made some interesting quilts and I wanted to learn the way she looked at fabric and how she decided to modify conventional blocks. I kept my mouth shut and finished both days of the class because of the money I had spent, but I have to say I have never taken another class from that person, nor did I learn much.