Saying many things usually communicates nothing. Horace Schwerin and Henry Newell, in their helpful book Persuasion, described their test of two commercials for the same car. Commercial one was single minded: It talked only about performance. Commercial two went further. It pointed out that in addition to exceptional performance, the car offered outstanding styling, a choice of several models, and excellent economy.
After showing subjects the two commercials, the testers asked viewers if either commercial might make them switch to that brand of car. Six percent answered yes, the performance spot would make them consider switching. But what about the second commercial, with all that valuable added information-how many were affected by it? Not one. Zero percent.
-Harry Beckwith, Selling the Invisible