I got reviewed on Airbnb by the Mysterious Disappearing Turks, so finally I know why they left:
Our initial communication was good with our host. He arranged our taxi pick up from the airport. However, when we reach the house, the neighbourhood was terrible. We didn't feel safe to stay there. The room was without a window with a restroom near. It is not a room that we can stay or sleep in. Our host opened the door and say they were sleeping. So we left...
We let people show up early as a courtesy, in case they have an early flight like these folks did. Did they expect we would entertain them/play host at that hour? Just for the record, the room does have a window, although not a very exciting one.