Quackery definitely exists. The problem with the term is that the label is too fuzzy, pejorative, and imprecise. According to the American Medical Association, the "operant word is promotion rather than intent."1 It is understandably hard to prove intent. Few would claim that Linus Pauling's advocacy of ascorbic acid as a cancer treatment is a deliberate lie. If, however, the criterion for quackery is the promotion of using unproven therapies, then the term becomes even more unwieldy. It would then include the large category of off-label interventions2 and unproven conventional medical practices3,4 that would make mainstream practitioners, who are presumably not quacks, very uncomfortable.5
We do agree that many cancer treatments and other unconventional therapies have been proven to be worthless and harmful. Perhaps there was also an intent to commit fraud. The most valuable response to such therapies has probably been carefully performed, controlled, clinical