Sorry you had such a bad experience. I have only taken a few classes over the years. My biggest complaint was that they show you how to start something but the class often ends before you get to the part about finishing. At one time I worked for a Bernina dealer. She had me work up a beginner quilting class. The first thing I planned to teach was the actual quilting process both by hand and machine. I made up single blocks of fabric that were sandwhiched and had a simple design drawn on them. If the students enjoyed doing the actual quilting then they were ready to invest in fabric, patterns and quilting tools. If they didn't like that step they were never going to finish a quilt. Over the years I have run into lots and lots of "quilters" who have made tops that were never quilted.
I often see quilts and quilted items being offered as classes in the shops I frequent. The first question I ask myself is do I need it and what would I do with it. I have a huge stash but very few UFOs. Being involved in the Linus Project has given me an excuse to purchase children's fabric. My own grandchildren are teenagers and would turn up their nose at childish fabrics.