Another danger, from the standpoint of glamour photography, is that light raking across a surface turns wrinkles into the grand canyon and pimples into mount rushmore. ;) Unless you're using some kind of diffuse lighting, you're going to get skin problems with anyone who hasn't got perfect skin, basically.
What I am getting at is this:
The angle of your lighting affects its apparent intensity (Karl's point)
The angle of your lighting affects the apparent texture of a surface
We saw the latter point graphically illustrated in the last photo (the one with the white bra) - much of the intensity of the image is from the texturefulness of the cloth, which is due to the sharp angle of the lighting. His model either had perfect skin or got some photoshopping. ;) (Humans who wear pants often have little skin-dingles around their waists from the friction of the waistband wearing the hair down and turning pores over)