I use Mike Deodato as my example. I really like his professional work; especially his covers. However, most of the con sketches I've seen from him have left something to be desired, so a few years ago when I had the chance to get something from him, I passed. However, Rich Henn was able to score a VERY cool sketch for me from him at Philly recently, so I'm thrilled.
I see your first point, Glenn. Perhaps calling it an "overpriced turd" obliterated any chance of pure objectivity and no artist is going to create something that everyone likes every time. On the other hand, having all the information handy helps to save a lot of time and money at cons.