Yeah, it's funny. You could almost have used those era comics as kitty litter box liner and they're still worth big moolah, but a little visible white fuzz on the binding crease on your 90s era stuff and its barely worth the paper it's written on.
Yeah, that's because they arrive at the comic book shop on Wednesday morning in big boxes with very little protection. Diamond basically just stacks them bare in the box in the amounts of your order and the alternating stacks (up/down orientation) are right next to another stack. What ends up happening is that the edges of the comics rub against each other in the box as they're shifted around which can rub the print off of the edge, so right away, roughly half arrive with minor stressing around the staples and slight visible rubbing on the crease.
At this point, if you're a collector oriented comic shop like ours, you bag them straight away. But here is the problem - we had to bag hundreds of comics, UPS arrived at like 9-9:30AM, you've got to go through and make sure everything arrived so you end up touching every comic pretty much at least once, if for no reason other reason than to count. And no one knows ahead of time which comics are going to be worth something 20 years later. If you're doing hundreds of comics, some of them are bound to get some stress lines while you're bagging the comics, even when you're uber careful. The hardcore comic guys usually came in at lunch to grab their pull lists and some of them would ask for backboards for the comics, so I'd go through the comics and grab the best ones and shove backboards in them all before lunch. And then I'd let them go through the stacks we had on the shelf to see if they wanted another copy, just so they knew we were letting them get the best copies that we had gotten in. BTW, some of these dudes would pick up 10-15 issues a week. We had a couple guys who lived out in the sticks - these were the days before internet ordering was a thing - who came in once every two weeks or once a month who'd basically be picking up a half comic storage box a month.
Anyway, I'd say that handling them as well as we did, only 30-50% of any stack we put out on the shelves were what could be considered 9.5+ near mint/mint quality grade comics. And I don't know of anybody who could have done it better than us, except maybe some hypothetical alpha neckbeard who wears antiquing gloves while bagging comics.
And if your comic book shop put them on the shelves unbagged, then you weren't really going to a serious comic book shop. Nothing anyone ever bought from a shop like that is worth much money.
Every once in a while, we'd get in a special signed comic or something and those would arrive from the distributor already packaged. That's pretty much the only way to guarantee mint or gem mint quality comics - certified in the package at production, shipped protected. Otherwise, mint/gem mint is about as rare as unicorn farts. Shit doesn't exist.