Its pretty hard to say 'once fired' unless your the person who did the firing from new brass. Stuff picked up at the range, there's no way to know how many times it may have been used. The 9mm, 40, 45 brass seems pretty safe, most don't mess with it where it gets used more than once and left on the ground.
But even actual once fired brass can be messed up. Guy I knew had bought this huge box of 7.62 nato once fired, 2k or more easily in the box, he was gonna load it, but never did. All lake city military stuff, it sat in the garage collecting dust. I skimmed a couple hundred to mess with. About half have loose primer pockets, must have gotten carried away with the swage removing the crimps.