@Andrea2559 So sorry you had your first nasty guests. Lke you, I've had delightful guests and sure hope i don't get any of these types.
My neighbors had a similar scenario- they rented their place for 6 months, while they were away, to a young woman who presentd herself very well. It wasn't an Airbnb rental, just private. Then she proceeded to rent out rooms, which both I and the neighbor right next to the house caught her out on and let the owners know. She flat-out denied it, even though the neighbor right next door witnessed people driving up and getting out of thier car and saying "Oh, yeah, this will be perfect!" No one says that if they're just coming to visit. I also found that she had listed the place on Airbnb- she went away for a week, and immediately 5 carloads of people drove up and started partying, keeping the neighborhood awake. I right away Googled and found the Airbnb ad, which she had taken down as soon as she rented it. Then she tried to tell me "Oh, that was never an active listing." If it was never an active listing, it wouldn't have come up on a Google search. The owners phoned her and read her the riot act, but she just continued- she was just more sneaky about it. In addition, when she was there, she held constant pool parties with her friends- there were always at least 10-30 people hanging out. Using the owners' towels and the hot water to shower.
I can imagine it's hard to know what to say when you've never had to write a bad review before. I would not mention the suspicion of them renting out rooms, as you can't prove that, but otherwise be honest, factual and brief. something like "Guests left the house in appalling condition- extremely dirty with many damages, and several missing items. Appeared to have been more people staying than were booked. Definitely not recommended."
Suggest you get some oudoor cameras for the future, and don't rent to anyone for a month- that's far too long if you don't live nearby and can't keep an eye on the place.