Nearly 1,000 people gathered at this year’s Scavenger Sale auction, aiming to nab one of the more than 30,000 local properties up for sale. The sale is the first step in a complicated process of trying to take over a tax-delinquent property so it can be restored, benefitting its community while returning it to the tax rolls. But many of the lots that go up are snapped up by hedge funds and large institutional buyers, or they stay unused for years, if not decades, while going through the sale again and again.