So, I'm just going to fast-forward the floor saga here.  Below, an example of staining I found after floor was sanded.  Tried further sanding; no luck.  Tried Peroxide; no luck.  

 I wish I had pics of me preparing oxalic acid on a hotplate on the porch in full protective gear.  Below is a test of oxalic acid on a stain.  "Before is the botom center, and "after" is the dead center.  Seems to work! Let's apply this bery dangerous chemical to every stain!

Same area, post-bleaching with oxalic acid:

 There are chemical processes going on here that I don't understand.  Note the phosphorescence and the "pucker" marks near where the staples were. What was once a dark stain is now a bright yellow...stain. And in other areas, there are stains that don't want to come up.

Imagine, in your mind, a series of photos in which I don the protective suit and mask, and sand the living hell out of the dining room and living room floors, by hand, using a 5 inch orbital palm sander, on my knees for hours, to get to all the stray dips and finish, and to attach the scratches and stains, etc, and, most importantly, to try to remove the yellowing, which I can only imagine is residual oxalic acid..  This takes a couple days, doing 300+ sq ft with 50 grit paper, then running out and using 60 grit.  And yet the living room still has stains.

So, a week or so back, I prepared for this contingency by soaking some steel wool in vinegar.  The resultant ferrous acetate is a salt that likes very much to react with tannins in oak, resulting in darkjening.  The very same chemical process (free iron ions reacting with tannins, also used to make "oak gall" ink) is what CAUSES water stains on oak. So maybe I can just stain the whole thing to match the original chemical stains?

Let's test an inconspicuous area, in the foyer:

Well, it definitely stains oak!  Maybe I'll just stain the LR and leave the DR natural?  The DR is looking decent now.  If I darkent the whole LR, though, I'll have to mask off the dining room.  And as long as the masking tape is out:

Note the LR floor looks really clean in this pic.  The lacquer is finally all up.  This is one of the least stained areas of this floor.  If you look closely, you can still see some ugly splotches. Maybe I need to take a break and think on this chemical staining thing... Besides, I just realized I have to go back over both floors with 80 and 100 grit paper, and I have a bunch of work to do that I can't do while the floor is drying.  The Saga of the Floors will return! (Saga of the Floors II: I really just did that).