As far as worth, I'd say very little. If they are trying to sell it they should pull all the nails at least. I've never done this myself, but did help someone else do it. A friend got a similar deal on some hardwood flooring. We pulled all the nails. Cleaned up any splintered bottoms and then ran it through a thickness planer to remove about 1/16" from the surface taking all the scratches and old finish off. we cleaned out the grooves and tongues and then he installed it. It looked as good as a brand new floor. He had plenty of extra to work with so he could avoid any holes, etc. It was well seasoned being about 50-60 years old. It was plenty tough on his planer knives, but a resharpen was a lot cheaper than all new flooring.