The wood floors we uncovered after taking up the carpet were in pretty good shape but they definitely need refinished. After we took up all the tack strips and staples it was about 120 man hours of sanding.
Bending over the machines for that long did a number on the back. But it was all worth it when we saw the results. After some filling and extra sanding most of the stains came out, at least as well as they could have.
We were hoping for hardood floors under the kitchen floor but after Joe and Dan chipped away at the particle board underlayment for an hour we didn't find any!