Thanks Colnago Mixte, mine was actually one of those bikes that had been left outside for some years(?).
This neglected bike's original San Marco saddle's cover had come adrift, and had been essentially turned almost inside-out from exposure to the elements (see below). I had to take a picture!
Paint was flaking off the fork crown, which appeared to be plated, but the haze polished off of the remaining paint (these 80's Schwinns have a very resistant paint that takes a ridiculously long time to polish smooth/shiny).
Luckily the wheels were in good shape, not usually a given with these 80's Schwinns (that too often have over-tight Atom hubs and flimsy Weinmann rims).
In the end it was worth the effort because this crust-bucket bike was only $40 at Goodwill with it's saddle falling apart and with a rusted-solid chain.