From The New York Times:
The story of paperback advertising started innocently enough: with babies, in fact. In 1958, the Madison Avenue adman Roy Benjamin founded the Quality Book Group, a consortium of the paperback industry heavyweights Bantam Books, Pocket Books and the New American Library. Despite the lofty name, the group’s real purpose was to sell advertisements in paperbacks, and its first target was the biggest success of them all: Dr. Benjamin Spock’s “Common Sense Book of Baby and Child Care.” A 1959 Pocket Books print run of 500,000 included advertisements by Q-Tips, Carnation and Procter & Gamble. By 1963, a 26-page insert in Spock was commanding $6,500 to $7,500 per page, and ads were spreading into mysteries and other pulps as well.
The bulk of paperback advertising came from tobacco companies, which were looking for new places to push their products after a federal ban on cigarette advertising on television and radio passed in 1969. Beginning in 1971, the Lorillard Tobacco Company began buying into print runs of tens and even hundreds of thousands of copies apiece at the astounding rate of 125 titles a month, often in pulpy volumes like “Purr, Baby, Purr” and “The Executioner #8: Chicago Wipeout” — not to mention the poetically if unintentionally matched “I Come to Kill You” and “Unless They Kill Me First.”