I literally have the best spot, but I don't want to give it away. Generally speaking, I tried to find a washroom that only one person can use that has everything in. Each of the floor on the engineering building has one of these and you could get in during peak hours, but Its hard to get, but non-peak hours you have about 50% chance. During the weekends there always empty, but I would guess a lot activity (Sex, I've seen a lot of condoms) other then dumping occurs here because these washrooms are kept clean and modern looking. But for anyone who is new to campus I would say this would be your #1 spot. The library also has single person use washrooms, but library is always packed.