She sucks on a zinc pill. Two hours later her symptoms have vanished. Whoa, thinks George. He begins researching zinc's curative powers. Other researchers subsequently report similar results.
Skeptics are quick to attack.
Among other criticisms, they claim zinc lozenges have a distinctively yucky taste that may have skewed the results. Zinc advocates don't give up. They argue that the lozenges used in the negative studies were of a type that inactivated the zinc. Were not, the Cleveland researchers riposte. But their conclusions are based mostly on the testees' personal assessment of their symptoms rather than on objective clinical measures, which doesn't give you much confidence.