BC - you hit it on the head.
In the basic clinic I attended, I think there were 7 attendees total. Of the other 6, not one incorporated what they learned to a permanent part of their game. One of them said at the end of the clinic that he felt it was a waste of time, because Bob suggested he change something. Mind you - even to my untrained eye, I could see the fatal flaw in that game. that's where my comment above came from - if you really think that you know more than they do, don't waste your money!
One couple applied what they learned for a couple of weeks, but mainly attended because their daughter was a pro, and since the daughter liked the clinic, she figured they would too.
One other couple - he applied what he learned for a little while, the wife decided she had too low of an average to really use what she learned (I disagree, but I digress...)
One gentleman was attending for his third time. He seemed to like the socialization of the clinic more than the instruction. Although he attended three times that I knew of, he said later that it didn't really help his game much.
After I attended the clinic, I started practicing every day. Sometimes at lunch, sometimes in the evening, before and/or after league. I found myself a practice partner who was a great complement to my game. I worked REALLY, REALLY hard. I've seen Bob several times since the clinic, and he is still pushing me to learn new things, because he knows I'm not wasting his time.
Several people I know have gone to the clinics on my recommendation. The unanimous thing that they say is that Bob makes bowling easy... Easy from the standpoint that you aren't exhausting yourself trying to throw the ball. He makes it much easier on your body. I went from struggling to get through 6 games to breezing through 12 in a regional.