Women, in turn, have an almost preternatural olfactory sense, one that appears designed for unconsciously sniffing out the mate value of prospective reproductive partners. This sex difference is probably owed to the fact that women evolved to be more discerning in their choice of sexual partners given the relative risk imbalance of casual intercourse between men and women. Historically, a man’s thirty or so seconds of physiological bliss often amounted to nine months of dangerous physiological stress on the woman’s body, not to mention a lengthy forfeiting of other reproductive opportunities. Fortunately, nature gave women a set of helpful olfactory tools to hound out whose seed was “worthy” (which means highest in adaptive value) of their uterine investment.
"Armpit Psychology: The Science of Body Odor Perception"
Women, take note that birth control could alter your taste in men. Sometimes, not for the best.