Boomerang kids

[Londonbug1]

I am not sure if this the right place for this but I really need to blow off some steam!
I have seen threads in here about empty nesters and how mothers long for their children to return home but.....
My ds finished university last year and is back home.
She has got a professional job which I know is exhausting but we are all working.
She is a lovely girl very charming fun but she is absolutely filthy. I am not talking about untidy here I am talking about dirty plates hidden in bedroom drawers. Pants in the wash(on the floor) with used sanitary towels attached. Bags with old rotting food left in them. The bathroom is trashed.
I think we that I am reasonably clean and tidy and am finding this impossible to cope with. It is leading to arguments and resentments and I can see it eventually ruining our relationship
I try to stay out of her room but I am terrified that we will end up with cockroaches or mice so I have to go in their and fish the worst bits out.
Anyone with any ideas I would be very grateful as I am at the end of my tether

Ugh that is not normal behaviour.

Not sure how to tackle it since at her age she should be a reasonable adult who is not a dirty pig, but sounds like something has gone wrong with her.

As I said, DD was at uni for three years, sharing houses with up to 6 other students. There were at least one or two every year who were squalid in their habits, never cleaned communal areas, room full of dirty plates and half-eaten take-aways for weeks. One girl vomited after a Christmas do, and when she moved out in March, the vomit was still on the carpet in her room, untouched.
There are a lot of very unsavoury characters who emerge from the pit with perfect make-up and straightened hair, and few would guess as to the level of filth they were happy to live in.
There are so few consequences that matter to them, losing a deposit doesn't seem to register and the anger or despair of the others in the house either irritates them or makes them laugh.