I purchased an exotic from Les three years ago at the Madison WI show. The colors are like the yellow/red/black on pages 119 and 124 of Collecting Early Machine-made Marbles. I purchased at the time the debate was raging and asked Les if my marble had come from the sewer excavation in Cambridge. He said it came from the estate of a long time collector and was legitimate.
I have no reason not to believe the marble is legitimate. BUT, I'm a former US Treasury Agent and often did early stage investigations prior to turning the information over to the FBI. I learned to look at events, not just what I am told.
Les stopped bringing CA's to the two shows I normally attend, Madison and Ottowa, after my purchase. It appeared that as the debate got hotter Les backed off of CA's. I purchased other types of CA's from him prior to the exotic purchase and they are easy to identify.
Did any others of you notice that Les was not selling CA exotics at say Columbus or Amana the last couple of years? Personally, I never bought into the exotic marbles, and since there are other manufacturers with great marbles I just put my money somewhere else.