You can see in the thumbnail of her save that the texture on her character's arm was correct (though I'm sure we'd have noticed this had it happened earlier), but in-game it was black when we loaded it. This problem started after loading my girlfriend's game a few hours ago. Now, I know that usually means it's running out of memory or VRAM, but the weird thing in my case was that it was only female characters' skin, you could see the polygons separated into their triangles (white lines between each triangle maybe it was the regular skin colour for just these lines?), and last, it seemed that depending on the distance and the angle relative to the camera determined the opacity of this black texture, which when transparent you could see the correct skin texture beneath it. So, for the first time ever since playing New Vegas, I saw the black textures glitch. Tried all the obvious stuff, and when launched the game again (which was maybe the fifth time restarting) to grab screenshots for this post, everything was back to normal.

Parts of black texture turn transparent depending on camera, and correct skin texture appears beneath glitched texture. Loading game that was glitch-free now has a texture error that turns the skin of all the white women we saw into pitch black triangles with light lines separating said triangles.

Fallout new vegas face texture