James Randi did a thorough study of faith healers back in the 1980s. A stage magician is the perfect person to debunk bunkmongers, because they all use stage magic tricks. He busted Peter Popoff, one of the worst of the lot. (His "hearing aid" was a radio receiver and his wife was backstage reading the information cards that the most faithful members of the audience had helpfully provided.) Unfortunately lunacy seeks its own level and he's been back on the air and busted several times since then.
One of the keys to pulling off a gig of faith healing, clairvoyancy, water dowsing, medium channeling, etc., is to have a huge staff on site: many more people than the ones who are obviously working the venue. They inflitate the audience in the parking lot, ticket line, restrooms, etc., and pick the ones with the proper attributes. The attributes are no surprise, what is a surprise is that they're so damn common. Suggestible, respect for authority, desperately wanting to believe, conditions that are largely psychological and not somatic.
Now, remembering that the healer is a professional, that little tap on the forehead is much stronger than it looks. The people who are chosen to be ushered to the stage are the ones that don't fight it and go down like spaghetti due to the helpful force of gravity.
The practitioners of the other paranormal arts also know the tricks. They're all either former stage magicians or people who have picked up the training, or smart people who figured the tricks out for themselves.
But to the extent that many conditions are psychosomatic or purely psychological problems, many of these folks actually try to help. After all, they get paid either way and a satisfied customer will send in ten of their friends. It's the old witch doctor routine. Put on a show and make the patient think he's going to be cured, all the while doing a "cold reading," asking a lot of questions, and just plain listening. Send them home with a placebo, a post-hypnotic suggestion, or just some good amateur psychotherapy, and the chances are good that the patient really will improve.
A friend of mine, before we met, was in a death spiral of drinking and missing work. Out of desperation he walked into an astrologer's storefront even though he's as skeptical as any of us. The lady never even pulled out her charts. She just asked questions, gave him some questions to take home that he could answer for himself with a little work, listened a lot, and talked some straight talk about being an adult and taking responsibility. He actually walked out of the place on the road to recovery. He never for a second thought that it had anything to do with astrology, and the lady never said it did.