I like the addition but there should be a toggle for it, also the clothes should get dirty as well. I would expect a melee character to be gore splattered but a ranged one not so much. Also we should be able to wash up with water from our inventory or go to a lake or something, adding the Prestidigitation spell would help too.
As is, Larian appears to be telling me to long rest more frequently.
This is a a problem. They are already forcing anyone who wants to talk to the companions to pretend to be lazy and weak and long rest after every small event. Adding the dirt makes it even worse for characters who prefer to be clean. Adding several ways to clean up anywhere would fix at least that part.