The "Sex Sells" principle doesn't just mean you put a pretty lady in an advertisement or throw in some subliminal sexual imagery. Sometimes, products are just marketed by bombarding you with pictures of men and women about to make sweet, sweet love.
Not only does this make the man or woman think "I will get laid if I buy this product", but it also puts an unconscious link in your mind between the product and lovemaking. Not a bad strategy. There's a reason this technique has been used for decades across the globe - it works. Let's take a look at some great examples of this time honored technique.
Note: Due to the fact that there's simply too many examples out there, I'm only going to show you one specific trope: like the picture at the top of this post, each has the chick on the left, the guy on the right, both giving each other "the look of love".