If what they're hearing is at odds with that, it's a sign to look harder. The same goes for a more edit-centered and widely used research tool, the mail questionnaire, which aims to pin down what departments in a magazine are working. A magazine like YM or Teen People, for example, might send out 400 to 1,000 questionnaires to subscribers to determine the audience's relative interest in beauty, fashion, health, relationships, and so on. You wind up intuiting less and less. Cover-subject testing at People suggests that a healthy tension still exists between editors' intuition and research.
Cover testing is good at the extremes.
If a subject you think has potential registers off the charts, that validates your hunch. But when you know you have a superstar, your gut is enough of a guide.