I think the author tried to be balanced. What I found was real sympathy as it seemed that everyone else made money off of these women, and they were treated often as a product rather than human beings. What they went through being "tested" was rather horrific, yet they did cheat.
There is a woo sort of thinking to explain why many supposed psychics end up as alcoholics. Practical thinking after reading this books leads me to think that it was simply being used, and trapped by their own cheating.