To clarify matters: Yes, it may be true that placebos don't have the placebo effect, but that doesn't mean that placebos aren't useful in double-blind studies. In fact, you can't construct a double-blind study without them. As I understand it, any conclusion based on a study in which a placebo was used will not be changed because of this new information.

Studies have also shown that people don't act nuttier when the moon is full, and that there is no increase in suicides and other emergencies around Christmas or any other holiday. Both of these ideas were once widely believed by mental health workers, ambulance drivers, police, etc.

Guess what: I read the other day that Easter lilies are poisonous. Do you suppose the old story about poinsettias just got transferred to a different holiday plant?