Vintage keyboards seem to be the dirtiest items I have come across collecting over the years. Most will look new with a complete parts off cleaning (the key labels seem to servive well enough on old keyboards).

I wish I took some pictures of my IBM PS/2 Model 90 when I got it. It looked dusty as hell on the outside but when I opened up the case it was wall to wall whitish fuzz like a pillows guts were stuffed into the case. Looks mint now and 100% functional.