Sexiness is largely subjective. One person's sexy album cover might be another's buzzkill. (Though everyone can agree that Prince is the bomb.) What struck us when looking at other lists of sexy album covers was just how boob-heavy they were. So we looked to balance that out. With penises.
Another principle we adhered to: Sexy music increases the sexiness of the artwork. The allure in images of D'Angelo and Sade is juiced up by the bedroom music wrapped inside. Which is why something like, say, Sugar Ray Lemonade and Brownies will not be found here. Sugar Ray is not sexy. Please do not try to have sex to Sugar Ray.
The sexiest decade? The 1970s, which produced 13 entries on our list. The era certainly gave us the most full frontal.
Oh, by the way, NSFW warning.