Supposedly, you can tell a lot about someone's stride pattern by looking at the wear on their heels. Whether that's useful information is another story. At any rate, when the cork or wood or whatever your shoe contains starts to show, it's time for a resoling. These shoes had rubber pads on the soles and need to be retired anyway due to a relatively low-quality leather upper, so I'll probably just replace them.
If I were to resole them, I'd have the rubber stripped and replaced with leather. You get a little extra grip from rubber soles, but there's nothing like crossing your legs during a meeting and revealing leather.