I've seen fairly bad MB fairs and some better ones. Not sure I've seen anything great. Whether the focus is on interest or size of class isn't really the point, is it? What's the point in these fairs? Sure, we want the scouts to learn something and interesting counselors are always better than just grabbing someone and throwing them in, but don't we also want the scouts to work with a counselor at a level more than they get in the standard class environment. Introduce yourself, find out about the MB, what's required, talk to your SM, get the blue card filled out, get the book, read it, prepare