You can feel them with your finger nail. I have got the lite ones out with polish but the deep ones, buy the time you get them out it distorts the glass enough so you can see it when you look at it and through it.
I'm almost done with my ground up build and trying to find window glass for my car that is not scratched. Is there anybody that has new or good glass? It's very frustrating when you replace every nut and bolt and have glass that has scratches in it.