I've found the opposite to be true. I could give a rats ass how the inside looks as long as it's cleaned of material and carbon. I want the outside as clean as possible and as free of media dust as possible, especially pistol rounds. An example is brass at has been reloaded with titegroup. It burns hot and Blackens the inside of the case permanently. Doesn't mean anything. Shoots just fine reload after reload. Crud on the outside of the case is what tears up the dies.