Apart from its original meaning in ethnography and as a borrowed term in psychology (Freud's "Totem and Taboo", his 'incest taboo', etc.), 'taboo' is a mere rhetorical device. Somebody would write or say, "X is a taboo subject but…" and then go on at length about it, although something taboo would be strictly speaking something that isn't even mentioned – calling something taboo is simply meant to titillate the naive. It's the same with books with titles such as "The Secret of…" (hardly a secret anymore if somebody publishes a book about it, most likely just has rehashed content), "The Hidden Power of…" (ditto), "The Forbidden…" (which authority does the forbidding these days? if the book nevertheless, gets published, it can't be terribly effective). Titillate, titillate, titillate. That's all the word is good for, although most people here are too jaded to derive thrills from the concept.
