I did The Man In Black (Black Smoke) from Lost and it got it right.
Here is how this thing works it asks you a bunch of a questions to narrow things down and get on the right track. These same questions it is asking are the same questions they asked somebody else who picked the character or person you were thinking of. In the event that you think of a character or person that nobody has asked him before. He will say I give up and then ask you to type in the name you were thinking of. Now the next time somebody thinks up that same character it has a base of questions to lead himself on the right track.
I think you can trick him if you think of a character on a TV show or movie that hasn't even aired yet.