What a mouth really says.

It really does seem to be a fact, I told myself, as my eyes wandered from lower lip to lower lip across the room, that all the less attractive traits of the human animal, arrogance, rapacity, gluttony, lasciviousness, and the rest of them, are clearly signalled in that little carapace of scarlet skin. But you have to know the code. The protuberant or bulging lower lip is supposed to signify sensuality. But this is only half true in men and wholly untrue in women. In women, it is the thin line you should look for, the narrow blade with the sharply delineated bottom edge. And in the nymphomaniac there is a tiny just visible crest of skin at the top centre of the lower lip.

Samantha, my hostess, had that.