The only thing that protects combination locks is sheer laziness. If the other solutions don't work, you can dial every combination. Thinking, "That will take forever?" Wrong. On a standard 3-number lock there are only 1000 possibilities. At 2 seconds a piece, you can try every combination in 33 minutes, with a 50% probability of hitting it in 15 minutes. I've broken a cable lock (4-digit) that came with a thrift store bike this way. Richard Feynman was apparently good enough to play with combination locks behind his back while chatting away, but he was a genius of course.