These definitions suggest that the promotion of quackery involves deliberate deception, but many promoters sincerely believe in what they are doing.
Most people think of quackery as promoted by charlatans who deliberately exploit their victims.
Actually, most promoters are unwitting victims who share misinformation and personal experiences with others. Customers of multilevel companies that sell health-related products typically have been persuaded by friends, relatives, and neighbors who use the products because they believe them effective. Pharmacists also profit from the sale of nutrition supplements that few customers need. In most cases pharmacists do not champion the products but simply profit from the misleading promotions of others. Quackery is also involved in misleading advertising of dietary supplements, homeopathic products, and some nonprescription drugs.