(See Feb 12, 2012) The Talmud in Nedarim 20a is talking about how terrible it is to flirt and stare at other women. Then it says, if you stare at "that place" of a woman you will have bad kids. Says Rav Yosef "and your wife a needa" Which means, "even your wife who will be OK at some point, but now that she's a needa you can't look there" (Ran). So you see that if she's not a needa you can stare at "that place", and when it says in 20b that you can do whatever you want with your wife it doesn't just mean anal sex, but also the staring and kissing of "that place". And then he will shut the light before actual sex (Tur O Ch 240).
Now this Tur in O Ch 240 is telling you the position of the Rayved (The position of the Rambam is in Tur Ev He 25). Now if you look at the Bais Yosef in 240 by the part of staring at "that place", he brings from the Rayved that our gemora (Nedarim 20a) teaches you that you may never look at "that place" period. I don't know how the Rayved understands Rav Yosef. The Gra in 25 tries to answer this by saying that Rav Yosef was only talking about having bad kids. In other words if she's not a needa you will not have bad kids, but it's still forbidden to look. Dochaik.
I hope this article will stop people from going to prostitutes. We all know how the media is bombarding us with sexual stimulation all day long, so tell your wife to shave 'over there', and go play with your wife. (See Feb 12, 2012)