Dave, you could teach most of these vocational classes!
They are really designed mostly for entertainment. I rarely teach them, there are a few that are hands on and are geared to a specific technique, method, and/or subject.
We have tried to offer some more advanced classes, but I think the names lost peoples interest? What seems to grab people are things like Artisan Breads or You go Grill...not Grilling Basics or Butchery 101
I guess sometimes you just have to cater to the majority audience?