Have you ever has THIS happen before?

I'm not sure what 'this' is. She does look odd with black legs and arms. Is that the issue?

I recently had a sim who's everyday wear patterns were put on his skin areas. Clearing caches fixed that oddity.

One time my entire sim was white. Like, a piece of paper white. I eventually figured out that her shirt was causing the issue. It's probably just bad cc.

I'm not sure what exactly the problem is? :/

She's shadowy from the neck down, like @TreyNutz said. She's not supposed to look that way.

Bad cc makes sims body charocal.

I had a toddler and a child get badly deformed once when Claire Ursine died and the social worker had taken her baby away.It started with glitches and errors in that save after the baby got removed and ended up with my girl in the military career and her little brother in law enforcement which was why they got deformed from those career outifts which weren't meshed for toddlers or children.It happend after the career flags glitched and the save got corrupted.

Yes, it has happened to me as well, usually it's cc related, altough one time it ocurred in live mode and the sim was completely black, it was only a silhouette, it felt like watching a shadow go on life but with a missing body :o
I believe that one time was related to my graphics card nearing it's end or showing it's age :/

Looks like broken CC to me.

I've only seen something like that for split seconds before, as my sim was loading in CAS, and once the sim loaded in .5 sec it was gone.

So I'd guess something is preventing the game from loading her body properly. Probably, as many have said, bad CC.