Thanks for your replies, guys! :)
Mojavpa, you're right, sex sells. But I think the only reason sex sells is because it's considered 'naughty'. Music videos and commericals go as close as they can to crossing the line and this sells because we have been so sexually repressed for such a long time that it is appealing to us. If sex was just treated as it is then nudity would not neccesarily be related to sex.
:)