Don't we all have bizarre dreams? They can range from erotic to racy, from weird to extremely creepy. What I understand about dreams, which can equal out to about zilch, is that it's our mind's way of trying to connect the dots of something that's bothering us. And, I don't think dreams of sex have anything to do with "sex" anyway.
As a writer, I get a lot of my "ideas" from my dreams. Nope, not saying that I'm lucky enough to dream erotica every night. I'm just saying that when I dream, my mind is free and open to ideas and thoughts. It's like my own fantasy playground, no one has to know if someone I'm completely unattracted to pops up in my dreams and turns out to be a porn-star-wannabe. Personally, I'd take a sex dream any night over a nightmare.