I know of a particular store in my area that purposely doesn't clean any of the used/consignment guns they put out for sale. They say they go out they way they came in. I talked a good friend of mine into a Model 10 they had, heavy barrel -6, that was dirty but cleaned up just fine and shoots great!

Easily 90% of the firearms I've bought over the years are used, or "pre-owned" haha, disappointed with 2 of them and sold them off for what I paid.