Since the library's main entrance is upstairs, many patrons go to the circulation desk first, and then are sent downstairs with their question. I don't know this to be true, but I suspect the circ staff gets malicious pleasure from some of the patrons they send down.
To wit: A woman carrying a few books, a stack of library CDs, and a portable CD player walks down the steps and comes to the desk...
Patron: The people upstairs said you could show me where a quiet room is?
Me: Sure, it's right down here. But it's not completely quiet - if someone is being loud outside the room you might hear them, but let me know and I'll ask them to be quiet.
Patron: Oh, I'm not worried about that, but I didn't want anyone bothered by me.
Patron: I want to practice singing opera, and I thought they said your quiet room was sound proof.
I waited for her to crack a smile, but she didn't - she was dead serious.
When I hemmed and hawed about the singing, she decided to just use a computer instead. She was listening to her Discman while using the computer, and after a few minutes started humming along with the music. There were only a couple patrons using computers nearby, and none of them seemed bothered so I let it go.
I feel bad whenever we can't accommodate someone's request, but I guess library patrons are just far more creative than library building designers.