I had tried to be friendly with Matthias and no regret about this. I was going to an another city during his stay and he directly booked the room without having a prior talk with me. But even the fact that I wouldn't be at home, he had the chance to meet me, my cat and to see the neighbourhood plus the room. I won't suppose that the flat was super clean because of my very limited time. But I did my best to clean especially his room before leaving the flat. Meanwhile, as a guest who even didn't clean up his own mess at home I think we should talk about this better. Well Matt, I could easily understand what kind of mess my cat causes and what other kind a guest could do.
About the cat; it's quite obvious from my listing, from my references and also from our messages that I had a very playful cat at home. And he had the chance to see how it is. I'd expect him to cancel his booking instead of using this to me as a disadvantage on his review, without any complain to me during our continious conversation of his stay. Locking the cat to the room wasn't kind or a solution at all.
Anyway, thanks for the feedback. I'll definitely have my lessons from my side. Wish the same for you.