Does Sex Necessary Sell?

An old advertising truism is that sex sells, but is it necessarily true? Is it a function of wanting what one does not have? Is the ability for suggestive images to sell products a function of satisfaction? If more people were satisfied with the sexual aspects of their lives, would it lose or diminish this power? Or is it simply a reflection of our psyches as sexual beings? Will this post generate more traffic simply by having the word "sex" in the title?