Thank you C'Frog and Bill, your input has been very helpful to me. Experience is what I need! If a copper was harshly "cleaned" and retoned improperly; would a second attempt at conserving the copper generate the same type of toning in time? I think such a second attempt at properly conserving the copper would give you the same finished look.
I think I would stay away from using a sulfur application to the copper. Not sure about what would happen if a Colonial, Half Cent, Large Cent or Token were set out in the sunlight for a long period of time. I would imagine the surface would have to be free on any contaminants that would cause a negative reaction.