Re: Sim bathing in random clothes Maxis only, no CC.
Did you have CC before? The damage may have been done then if you did.
But if you're okay with Mods, MCCC and its Dresser module (that mod on MTS you mentioned is probably way too old) can help you fix affected Sims.
Also, Sims4Studio's "Disallow CC for Shower" batch fix can help fix your CC so it doesn't happen again.
Google them both, and if you need help, let me know. đ