The Psychic Mafia by M. Lamar Keene and Allen Spraggett (1976): M. Lamar Keene was a psychic huckster in the 1960's and 1970's who developed a conscience and decided to reveal the tricks mediums and psychics use to bilk their customers. This book is the result, and it's a fascinating glimpse into a world which, if anything, has grown larger and more fradulent in the nearly 40 years since The Psychic Mafia came out.
Keene calls his former compatriots 'the Psychic Mafia' because there's widespread communication and sharing of information between them, whether they call themselves spiritualists, mediums, or psychics. A medium in Florida may be able to 'read' astonishingly detailed facts about someone 'new' because information has been sent in advance from the medium that person usually sees in Maine. And so on.
This was true long before the Internet. Imagine the ability to instantaneously share information about clients now!
Keene goes into other tricks of the trade, most of them fairly basic sleight-of-hand and mentalist stuff. Chiffon turns out to be the fabric of choice for ectoplasm in a darkened room, for instance, as it looks remarkably smoke-like when the right lighting is used. Other basic mentalist skills such as pick-pocketing, palming, cold reading, and ventriloquism also fill the medium's arsenal.
There's a real sadness to many of the stories Keene tells, as people are defrauded of hundreds or thousands or tens of thousands of dollars by a spiritualist network from which Keene can glean no stories of 'real' psychics...or even people who believe they're real psychics. The entire enterprise seems corrupt, and seems to have been corrupt since the birth of modern spiritualism in America in the mid-19th century.
Along the way, Keene also coins a useful term -- 'true-believer syndrome.' He applies it to the customers (or dupes, or rubes) who continue to believe that they've experienced real spiritual phenomena even when, in some cases, the medium himself or herself comes clean and admits to that person that everything was a fraud. I think you can imagine how this phenomenon plays out again and again in areas other than spiritualism. A fascinating book about a fascinating (and disturbing) topic. Recommended.