"The dairy industry tried for 20 yrs to convinve you that milk is good for you (it's a lie, but they tried anyway), and the sales have gone like this [down], and then they tried "Got milk!", and the sales have gone like this [up]. "Got milk!" is not even an ad about a product, it's an ad about an absence of a product!" "APPLE SPENT A FORTURE ON ADVERTISING! YOU'LL NEVER KNOW IT."
Steve Jobs on Marketing