Why don't the wheel's work on the guest's chair on the Daily Show? Jon Stewart's chair rolls just fine. But every day somebody comes on the show, pull out the chair, sits down and tries to move closer to the desk and the chair just tips forward. Some of them just move farther forward in the chair, leaving about a foot of empty chair behind them. I'm waiting for the day when some engineer comes on that show and they sit down, the wheels don't work, and they get up out of the chair, flip it over on the desk and look at the wheels and say "Oh, there's a cap to a ballpoint pen stuck in here." And they'll whip out a pocketknife and pry out the piece of plastic, flip the chair over, sit down and roll right up to the desk.
Meanwhile it makes me wonder how many people notice this besides me. Apparently not any of the guests or they'd be asking to practice with that chair ahead of time.