I recently bought two used Wilson K 6.1 95s from a sporting goods store that had been demos ($29.95 each!). The idea that a racquet slowly loses responsiveness and playability over time is one that's been discussed plenty here, but I was just wondering if it was possible to get idea of how much wear and tear there is on a racquet that had been a demo. I took them out for a hit yesterday and they felt pretty good, but I'm no expert (not to mention that I didn't have a new K 6.1 to compare them with). Is it even possible to get a general sense of how often demo racquets are restrung? FWIW, the frames themselves look decent - about 7-7.5/10, maybe. One says Karbon Black on the side while the other says Karophite Black.