If the keyway looks like a donut, it's vulnerable. How much is, of course, the subject of much debate.

As to what to do: Either re-cycle them or have fun breaking 'em. You can try all the silly tricks to see if any work. Have a few of the fellas over in your garage with some beer and you have boys night in with power tools. Make certain to have an E.R. pool when the power tools come out!