One of our group was woken up in the morning by a man letting himself into the room where she was sleeping, to leave a bag of linen for the next guests, which was inappropriate; a heads up would have been good. Someone also apparently entered the apartment and removed the key lockbox while we were out, which caused a stress when leaving because we couldn’t find it. Again, a heads up would have been appropriate. It's dodgy to have people freely coming and going without any communication.
Something weird with the plumbing - bathroom taps weren't fixed to the sink, and a strong smell of sulphur whenever they ran; a stern welcome note warning guests not to use any spare linens found in the closet; one unusually small towel per guest