Why did my sim turn pitch black?

Yeah, thanks DA, I don't have any CC myself, but I keep up to date on the creators forums whenever there is a new update, patch or ep, so I can try and help people with CC. I know with both the patch and Ambitions the Creators were mentioning a whole large number of skins, hairs, and makeup was getting problems this go round as how CAS is used was changed in Ambitions, so it negatively affects CC. But they mentioned that a sign that a skin default was conflicting was the sims would go black or take on the color of a CC pattern a sims is wearing. So I thought I'd mention it to Leah there, so she could know what her problem was. As they said you just had to uninstall the default skins and then reinstall them to correct how the game saw them, then put sims back in CAS and reapply the skins to make them look back to normal - at least on most of the skins this was considered the fix unless there was another conflict - like with tattooed skin. That, they said had to be removed from the game.

But I had never heard of any way to get a household sim into CAS, so I had no clue. I usually don't pay attention to what mods actually do, just their names and how to fix them, and how to distinquish if they conflict. What is SC anyway? That one is foreign to me or does that stand for Twallans Super Computer perhaps?