I have tracked several auctions on ebay over the past few years and the answer appears to be, "occasionally." I have seen some bring a decent premium while others priced very similarly never receive a single bid. The biggest problem in trying to sell a single impaired (circulated) clad proof is that the entire non-impaired proof set can be bought very cheaply. I have no idea why someone would shell out a few bucks for an impaired proof when the entire set can be bought for just a few bucks more in most instances.