Most reputable therapists are in the field of treating patients with PDDs because they care. They want to make an adequate living, but they aren't expecting to live a lavish lifestyle on other people's misery. Ask about costs. If the answer sounds like mumbo-jumbo instead of a truthful accounting of expenses, find the door. Be especially careful of any method that claims to cure PDDs.
People do get better with proper intervention.
They function better in the world, they feel happier, they're able to enjoy the benefits of being a relational person. A stranger might never know that they once carried the label of PDD-NOS, atypical PDD, or autism. As these books make clear, smart people can be taken in, including idealistic young therapists who themselves end up bamboozled into the wrong camp. Perhaps the most important thing you can do to protect yourself or your child from therapy scams is to trust your own intuition. If it feels wrong, it probably is.