My friend has granite or marble counters (black stone). They don't keep such a clean kitchen. And the counters... I don't like to touch them. I just can't tell if they simply need a good rub down with a counter cleaner, or if they actually need a light polishing of the stone itself. I have Corian, and I can get a like-new finish by lightly polishing with wet soapy brillo. How do you handle the stone counters?