I clean all of them before I shoot them. I mostly buy used guns and some of those would have had issues if I hadn't cleaned them. I've had magazines full of dead baby spiders, mags with broken springs, revolvers full of unburned powder to the point cocking them was difficult. Bores on rifles that looked like someone painted them with thick flat black paint from shooting a lot of .22LR. An Astra A-100 was full of some kind of polishing compound that had splattered all over the gun, making the previous owner think it was rusty. Good deal for me, one of my best on GB. And a couple of guns had lube that had turned into a concrete or plasterlike substance due to age that had to be scraped out before they could be shot. And a lot of used guns just needed to be cleaned, they were nasty. I kind of like guns on auction sites that are really dirty as it seems to keep the price down.