Picky guests are hard to predict, but be careful of guests who have never used AirBnB.
I have instabook, and last summer had a couple that had never used the platform before. They seemed fine when I contacted them after checkin (no complaints) but after leaving complained about the "uncomfortable sofa" (which is Restoration Hardware). Also, I allow pets, and they came with their dog. They should have been grateful BUT they rated me a 2. A 2!
In short, perhaps do not accept guests who have never used AirBnB before, but more importantly, forget about ratings. The system was designed to drive you crazy.