Spidernet in the ceeling and tapestry falling off.
Well, I made a booking on a room without a veiw, which I assumed was, okay, I'll probably get a window towards a brick wall or something, and ended up in a basement. with no window at all. And the elevator was broken so you had to go down the stairs past the mens urinal. The air circulation in the room was suffocating, there were no flow of air, even though the door was thin enough that you could hear when someone was talking in a low voice in the corridor. One night there was drunk people fighting and it wasn't resolved until 5:30 am.
Also there was a warning in the bathroom that if you'd didn't close the door during and after a shower you would set off the hotel fire alarm, which made getting ready in the morning a torture hence the horrible ventilation.
Even though it said when I booked the room that I had free internet wifi. It was limited to the lobby and you had to log in every 30 min, which allways was a hassle. And if you wanted a decent connection you had to buy access to another internet.