To accurately grade records you must listen to them.
I know there are specialists who say they use a zillion-watt bulb and 30 years of experience. But often that is still not good enough.
You can have vinyl that looks really nice -- maybe just a few hairlines and other superficial marks, nothing that even approaches an actual scratch. But this record can still play with surface noise. You really don't know until you put the disc on the turntable.
One of the big vinyl disappointments I had occurred about two years ago when I bought a copy of Derek and the Dominos' Layla and Other Assorted Love Songs. I took a really good look at all four surfaces of the two records and was confident they would play nicely. My error. They played with enough light crackle to convince me I had made a mistake, even at £3.00 for the album (It was the RSO reissue).
I've even had vinyl that looked almost new, shiny with a nice gloss, that then played with surface noise. My idea is that it was the old styluses or needles in the '60's and early 70's that could do this kind of damage if they were not correctly maintained and replaced in a timely manner.
See the attached photo of a Japanese reissue of Mr. Blue by Fleetwoods as an example for vinyl that looks great but plays with light crackle and even a hint of distortion.
On the other hand some of theold 60's records, particularly the original lp's of the Beatles and Rolling Stones, sometimes sound better than they look. This seems to be because the vinyl used then was heavier and thicker. It could take more punishment before any serious damage showed up in the sound.