Oh Cindy, I feel your pain! This just happened to me and my family at the airbnb we rented in Glasgow. I believe we received an unfair review since our host was probably expecting a negative review from us due to some odd behavior from him at the beginning of the experience.
I spent 1/2 a day tidying up after our 8-day stay (myself, husband, 2 kids who I only allowed to eat in the kitchen). I ran the dishes. I cleaned up every scrap around the 2-bedroom apartment. I wiped down the tabletop, countertop, sink, etc. I even took photos before leaving and felt genuinely pleased with how we left the apartment. On the other hand, I was pretty disappointed in his place - which had stellar reviews. It was dirty - the shower drain was clogged, the kitchen sink was coated in grime, the toaster had a layer of dust and bread crumbs on it. The beds were uncomfortable and the WiFi was abominable (.5 mbps upload speed, and I had to do work while I was there!). I wanted to leave a bad review, but I didn't want to be mean, so I didn't leave a review at all.
Our conflict all began with our arrival time. It's my fault that I didn't let him know until a few days before that we would be arriving in the "late afternoon / early evening" - and then the day before, I informed him that our train would arrive at 8:15 and we'd be at the apartment at 8:30. He replied that we HAD to be there by 6 PM as his dad would be greeting us and needed to be out of town. He was rude - didn't apologize for not being clear in the beginning about a check in time limit. We ended up buying new train tickets to arrive by his dad's deadline. I was nice about it, too, but I was pretty upset about the situation.
His review complained about our arrival time and failed to mention that we capitulated and rearranged our schedule for him. Then he complained about "rubbish left in bags" in the kitchen - these were 2 bags of plastics and paper, for recycling. The apartment building's trash room didn't appear to have a recycling option, so we thought it'd be better to leave it in the apartment for the host to dispose of responsibly. And then lastly, he complained about "wet towels left on the beds." Well, for this I'm truly sorry - yes, it turns out my husband left a damp towel on the bed after showering on the morning of our departure.
But seriously, I left the apartment as I found it - in fact, some things were cleaner, like the kitchen sink! And now I feel terrible and am second-guessing my ideas about cleanliness and manners. I didn't expect a host to be so put out by having to dispose of 2 small bags of recycling and a single towel. And he didn't take any responsibility for his lack of communication regarding check-in time.
I'm going to have to get a voodoo doll to take out my stress over this!