What's weird is that when that website (and the 20 Questions Toys) first came out about two years ago, it seemed to guess correctly every time. I don't know if they changed the algorithm, or if it just has too many objects/concepts in its memory, or what. But I remember it being much more accurate, and really impressing all the guys in my office that tried it out.
Similarly, when the Song Tapper website came out it easily guessed almost every song I tried on it, but when I showed it to my son last week it missed three out of three on some rather common tunes.
Maybe computers are getting stupider!?