Clean bedding is a basic hygiene standard, yes?

[Dirrrty]

Ex H has taken our two children several hours' away to visit his parents, along with his new girlfriend.
They live in a three-bed house; one single bed, two double.
My 12yo has phoned me grossed out that he's been put in a bed that his 15yo cousin had slept in the night before (if not longer than one night, he's not sure), and the sheets weren't changed. My 7yo was put on an uncomfortable sofa for the night. During the night, she was so uncomfortable that she got up and asked to be in the bed with ex and new gf. I'm not happy about that at all. He should have known she wouldn't be comfortable on the crappy sofa, and imo, the two children should have been given the double bed, new gf in single bed, and him on the sofa downstairs. He's a selfish arsehole though, so it wouldn't occur to him to think of his children before himself and new gf.
New gf is heading home tonight so my son asked his grandmother if he and his sister could sleep in the double bed tonight, and would she please wash the bedding. (Ex is out with new gf for the day showing her the nearest big city, so kids are dumped with the grandparents doing absolutely nothing, just sat in the house.
I'm not happy about that either.) Ex-mil has told my son she is too busy to wash the bedding (my son says they are just sitting about).

But my aibu is, surely it's basic hygiene when having guests to give them clean sheets???

YANBU - of course they should have clean sheets
YABU - it's not going to kill them, sleeping in used sheets, meh whatever.

Comments re the sleeping arrangements welcome too. Thank you.

OPs son is upset about sleeping on sheets that have been used. Some children are more sensitive to things like that. His little sister is upset that she’s sleeping downstairs on a sofa that is uncomfortable because it’s not flat. (See photo) She can’t sleep much and now hurts.
The kids were told they would be spending time with their dad and cousins doing things, going into town etc. Instead they have hardly seen their cousins and their father has gone out and spent time with his girlfriend. He lives with her and only sees his kids EOW usually, yet he’s not spending time with his children.
Whilst the kids have been left with their grandparents, they have tried to engage but their grandparents but they aren’t interested. They can’t even watch a film because grandad rules the TV with sport They’ve been sent to the summerhouse to spend their time on tablets and are being ignored.

Hardly a great half term for them. If they’re not spending time with their family, they may as well have stayed home. They could have had a half term with mum, friends, swimming, doing nice stuff and surrounded by their own stuff sleeping in a comfy bed.

How happy would you be being sold a holiday of fun with family you hardly see and instead get to spend very little time with family, being ignored, sent away, being stuck on tablets with uncomfortable sleeping arrangements. Probably not very happy... and you’re an adult that could take yourself off out somewhere.