JUDGING from the best-seller list, the total woman of the '80s is expected to be an expert in bed as well as in the kitchen. The G Spot, the latest hard sell in a soft market, appears destined for the No. 1 slot. There are already 150,000 copies in print. Six book clubs have picked it up, and paperback rights have been sold for almost half-a-million dollars. The Love Muscle is a G-Spot spinoff in a different package. The two together threaten to start yet another Trend, this one taking us back to the good old days of sex in the dark, before the eye-opening research of Masters and Johnson.

The story of The G Spot begins in 1950 when Dr. Ernst Grafenberg, a German gynecologist, published an article in the International Journal of Sexology which languished in semi-obscurity for years. In it, he pinpointed a previously unknown erotic zone located "on the anterior wall on the vagina along the course of the urethra . . ." Alice Ladas, Beverly Whipple and John Perry claim that when properly stimulated the area swells and produces an orgasm that is distinct from a clitoral one. Out of 400 women they personally tested, all were able to locate their G (named after their mentor) spots. Some of the women, according to Ladas and company, were able to ejaculate a fluid through the urethra during orgasm. The G spot, claim the authors, is the vestigial prostate gland in women -- made up of tissue similiar to that found in men. But instead of defending this astounding revelation with hard-core, scientific data, they choose an inordinate number of soft-core testimonials (including one from a trainer of seeing-eye dogs) from women with born-again sex lives, who believe in their spots.

The authors' gender blender goes even farther: Not only are women capable of ejaculating, but men are capable of multiple orgasms. Man's second, and equally important, sexual organ is the prostate gland which, if given equal strokes, is capable of producing an orgasm distinct from the normal one. In case this is previously untraveled terrain, The G Spot comes complete with road maps.

For the female traveler in search of her new Big O, how you get there is not half the fun. Ladas et al. don't stress foreplay, which we are warned can only lead you astray. Nor do they call for a return to the missionary position. In fact quite the opposite is the case: "Man is designed as a quadruped," they quote Grafenberg as saying, "and therefore the normal position would be intercourse a posteriori." This provides men the maximum thrust, because, according to one male source, "certain women really want you to pound them."

It seems that women who, after all these years, still have not discovered their sunken treasure, may be suffering from vaginal amnesia -- thanks to the recent decade's emphasis on clitoral stimulation. But don't despair -- therapy is readily available. The authors correlate the inability to have a G-whiz orgasm with a weak "pubococcygeus" muscle. The muscle in question "runs from the pubic bone in the front to the coccyx (the tailbone at the end of the spine) in the rear. In animals, this muscle wags the tail." A healthy sex life is a healthy PC muscle. Coincidentally, author Perry (an ordained minister, psychologist, and sexologist), has invented an Electronic Perineometer -- the Cuisinart of sexual aids -- which "effectively measures the tone and health of pelvic muscles."

The G Spot stresses the importance of Perry's machine in a chapter all its own, and proceeds to lay out a series of exercises that will quickly put the PC muscle on the road to recovery. In case the reader thinks this is not a crucial matter, we learn that "tension" in the PC muscle can lead to a number of problems: lower back pain, cystitis or, as in the case of one of Perry's patients who refused an invitation "to take advantage of free therapy" -- cervical cancer.

The Love Muscle, whose prose makes The G Spot read like Sigmund Freud, is the first signal that the PC muscle will be with us in the '80s. Bryce Britton quickly gets to her empirical evidence in chapter one: "At this point, I can sum up all the scientific research for you -- if you don't use it (the PC), you lose it." This book is much more of a "how to" manual than The G Spot. It includes countless questionnaires and quizzes which read like a high school aptitude test: "Women enjoy sex as much as men. True or False?" Britton approaches her material like a Zen Buddhist, describing Grafenberg's orgasm as "The Inner O." Orgasms for her are a state of mind. By simply "concentrating" on the PC muscle some women "become so in touch with their sexuality that they become able to have orgasms at will, with no touching." Pretty tricky.

Both these books attempt to reopen the debate over the vagina vs. the clitoris, which has long since been put to bed by Masters and Johnson. In a classic 1970 essay by Anne Koedt, "The Myth of the Vaginal Orgasm," she asserted that women's orgasmic potential had been stifled because "normal" heterosexual intercourse completely neglected the clitoris. Her findings were confirmed by Masters and Johnson, whose empirical study concluded that more women were able to reach orgasm through clitoral stimulation than through vaginal stimulation, and that there was no evidence to suggest that a clitoral orgasm was any different from a vaginal one.

Ladas, Whipple and Perry would like to unseat Masters and Johnson as the top-ranking team on women's sexuality. But their slim volume -- regardless of an enormous promotion campaign -- will not even get them into the same stadium. No one would argue that the vagina is an insensitive -- or irrelevant -- area, but Ladas et al. have simply figured out a new angle to maximize male pleasure, while beguiling women with the promise of still another new kind of orgasm. While the authors begin this book with a mild attack on the limitations of Freud, they end up wholly endorsing his original notion that women mature from clitoral to vaginal orgasms. When all is said and done, the book tells us to grow up. In case the reader takes the real message too seriously the authors caution: "Don't use the information in this book to set up new standards for yourself or your partner because, by doing so, you may undermine the pleasures that are already yours." Agreed.