I had a somewhat similar situation with one of my very first bookings. Daughter booked for herself and her mom, and they checked themselves in very late at night, so I never met them in person. All communications with the daughter were fine. About 1/2 hour after my checkout time, I walked up to the Airbnb property and saw a car with the hatchback open, license plates from the state the guests were from, etc. Figuring they were my guests, I introduced myself politely. Mind you, they were late checking out...so it was a little awkward, and got a lot more awkward when I noticed the huge packages of TP and paper towels I had purchased just prior to their arrival sitting on top of their luggage in the back of the car. Yikes! The daughter turned red and ran inside, and the mother just sort of stood there.
I took a deep breath and said, "I'm sure you're aware that my checkout time was 1/2 hour ago. Are all of your belongings out of the house? No? Well, my cleaning helper will be here any second." I looked very directly at the unopened packages of paper products in the car, and turned on my heel, pretty ticked off, but at a loss for just a second.
I walked down the block and took a few deep breaths, rehearsing what I would say, but they had driven off when I returned. Lucky for me, they had tossed the paper products in the front door. Now I lock supplies up. Sigh.