I'm dealing with this right now. A guest who checked in with a smile, reported no problems at all with the stay, and quietly departed the following morning. 3 star overall (my first ever) as well as saying we did not communicate with him (there were plenty of messages where we did, but he never answered) and he also stated the photos of the home were not the property listed, which was clearly not true. 3 stars as well in location and value.
I reported this to AirBNB and I really hope they take the review down. He actually tried to cancel the day before, and couldn't because of the refund policy, and I think he left this review in anger. Also, he specifically stated the kitchen was unclean, which made no sense since we just had a professional cleaning company come through. I was looking around the kitchen to try and find some clue about what he was talking about, and now believe that he may have actually pulled the stove away from the wall (which would have taken a lot of effort) since there *was* a dark grease spot behind the appliance (I cleaned it today). That's clearly someone looking for a problem to give a bad review.
I am hoping AirBNB is sensible. I have a recent streak of 4 star people, for no apparent reason, and its upsetting this guy is trying to pull something like this now.