Oh, and jack, I understand what you are saying...I come from ancients where the rules are much different. I also know that proper conservation is not frowned upon in world coins either as long as it is done properly. Just like I took the time to learn how to properly clean an ancient coin...I wish to also properly learn to how to conserve some of my ratty world coins as well. I assume that like with ancients, they are procedures that can be taught and learned.
I would never tell a person to scrub a modern world coin with a wire brush

The most advice I have given concerning modern coins is a dip in distilled water to help thin grime and dirt and the few methods I know that will effectively treat Bronze disease as I have had to do this sometimes with my ancients.