About half of my house has original "face nailed" (don't know the correct term) wood floors. Though the nail holes have a lot of character, the floor needs to be refinished. I know the nails are at various depths and will instantly chew up a sander. As painful as it would be, I have thought of setting all the nails deeper and then sanding, but that leaves me with the same basic problem... holes in the floor with discoloration around them. Any suggestions? It is sacrilege to set the nails and fill in the holes?