Many years ago I had a used CVA Mountain Rifle come into the shop. It had a broken ramrod, a lock that did not work and a pretty rough bore. I took it home over the weekend. Replaced the ramrod with a spare I had laying around, cleaned and adjusted the lock and scrubbed the bore extensively. The old gal cleaned up pretty well and I sold it the following week if memory serves. It didn't come back with complaints, so I assume she was a shooter.
Nearly all used guns will clean up to a reasonable standard and most of 'em will put bullets into a deer's kill zone just fine.