Thank you for sharing your experience and research. I have discovered that wear is not always evident in a visual inspection. I have purchased records from the sixties and seventies that are stated by the seller to be “NM”. They look really great — shiny, black, no scratches etc.
You have stumbled upon the reality that you cannot see sound quality. The only way to know if a record is good or not is to play it. Then depending on all the little details of how this is done the record may be one and done, or play beautifully long after you are dead and buried.
No one knows anything about how good a record will sound until it is played. A couple months ago while waiting for Tom Port to find me a White Hot Year of the Cat I decided to take a chance on a "good deal" on Discogs. The cover was damaged so it was cheap but the vinyl was supposed to be NM so I took a chance. This copy was Mobile Fidelity and the vinyl did look to be NM, maybe even unplayed. It was dead quiet. Not a tick, not a pop. Not much else, either. Easily one of the worst sounding records I have ever heard! Plus it had a warp, that thanks to my clamping system flattened out enough to play, but was bad enough the seller refunded me and never even asked for this POC back.
It was such a POC that I sent it along to Tom to get a good laugh. Tom makes his living finding records that sound unusually, incredibly, unbelievably good. You cannot tell by looking. He has to play each and every one. This MoFi was such crap, sort of wish I kept it just to show the few who come by just how awful a reissue can be. Even from MoFi.
All the really important information on a record is captured in groove modulations so small they are on the order of the size of a large organic molecule. On this scale even the tiniest barely visible speck of dust is huge and will make a pop or crackle when hit. No way anyone is going to see this. Even with a microscope, you would need an electron microscope to see the sort of damage that can be heard easily.
So just play em. That’s what I do. Play em. And don’t worry. The magic, when it’s there, never really goes away.