Finally got some pics up of what I'm talking about.
In front of both the master bathroom (first pic) and entrance to the bedroom (second pic) you can see how the wood is much darker than the area to the immediate left/right of the doorway. The discoloration is much darker than how it looks in the pics, but you can still get the idea of what I'm talking about. It looks as though the stain was worn off and the wood was dirtied from lots of foot traffic.
I also noticed some gaps a little wider than the thickness of a dime between a couple of the boards as well, but they'll be covered by a bed so I'm not too worried about it.
Will this require refinishing, or can all of this be cleaned off somehow?
There are also small holes in the floor from where the carpet tack strips were nailed in, and a couple of ~1/4" holes drilled by a cable TV installer when he ran the coax up from the family room ceiling below (I'm guessing because doing a good job and going through the walls would have taken longer than 2 minutes). I'd like to think I could use wood putty to fill the holes, but I doubt they'd look right after staining. I'm not that
worried about the holes, but if there was a way I could fill them in without replacing the boards I'd love to hear it.