In writing advertising it must always be kept in mind that the customer often knows more about the goods than the advertising writers because they have had experience in buying them, and any seeming deception in a statement is costly, not only in the expense of the advertising but in the detrimental effect produced upon the customer, who believes she has been misled.

The business biography of John Wanamaker (The Macmillan Company, 1930), p. 391