Oh my gosh Laurene! I have one of those from November that I just spotted yesterday! Maybe we had the same "ghost guest"!
let me explain. My guest was a no-show on the actual day he booked. I left messages throughout the day since I live at the space (I rent a bedroom). Finally, around midnight he contacted me and apologized. He said he needed the following day and had made an error. He asked for a refund of his $38 dollars and I politely told him to go through Airbnb booking but that I thought it would not get him a refund.
he contacted me again, said I should give him his refund!
So back to the new review system. He managed to leave me a negative " NO TOWELS, NO SOAP, NO TOILET PAPER, NO PILLOWS" in the guest suggestions or feed back whatever it's called.
maybe some irritated ghost guests of yours might have done the same?
airbnb say it's fine they have the right since they booked!