Ed Topliss has a problem. Two and a half years ago, he was approached by a publishing executive of dubious credentials, who said, “If you can write a grammatical letter, you can write a sex novel.” Since then, Topliss (who also writes under the pseudonyms of Dirk Smuff and Dwayne Toppil) has written one sex novel each month for $1,000 per book. According to his formula, that’s 10 chapters of 5,...