The king always got dirty to make an excuse for you to give him a bath. He wouldn't wash or take care of himself while in the tub.. Instead, he ordered you to do it.

He enjoyed that he was putting you in extra work to make it harder on you, and he liked ordering you around to clean him

Sukuna sat there in the tub full of water relaxing, as he waited for you to come in the bathroom, after you gotten everything you needed