The nude female skin included in the file isn't even female. The proportions are quite distinctly male as evidenced by the placement of the nipples being way too far appart and thus rendering them on the side of the breasts rather than the front when it is placed over the female upper body mesh in the mod. The mesh file of the supposed nude still distincly shows the folds of the bra (rendered normally as a folded up, dirty off-white cloth going around the upper body) giving the topless characters lumpy shadows where the bra was.
In other words, this was not a 'hidden' nudity thing. The males can be rendered without shirts and clothing made with exposure of various parts of the upper body. The female was made the same way, and since the nipples would never be shown, it didn't matter that they used the male skin 'skin' for it as well.
I think this could come in handy. So much to say. Um... First Post!!!