Howdy Camille,
well I guess if you have a mouth full of coke or beer while you wre cleaning your guns and someone tells a really funny joke...
Two of my '73 carbines are charcoal blue. The first one I got in 2000 (won it, yeehaa!). First shoot I took it to, my guncart tipped on uneven ground with the carbine not secured, and it plopped down on the gravel
Put some dents in the AAA wood and a ciouple scratches on the barrel. So much for a pristine gun, hehe. And later I left it in one of those cheap cloth "socks", the type that are made of thin foam and the end folds over. I thought it would breathe, but it didn't and it surface rusted the mag tube. The rust came right off with a bit of steel wool and ballistol, but so did the finish, so the mag tube is patina'd now. Other than that, the barrel has a slight wear where it leans against the guncart, and about half of the finish is worn off the butt plate, but it's still a very pretty gun. The other carbine I got about 3 years ago and it still looks brand new.
My engraved '51 conversions are charcoal blue, and they have seen a pretty fair amount of use and are just a wee bit worn at the muzzle and end of the ejector, and at the hump at the bottom of the barrel. Barely worn on the front edges of the cylinder. The worn places do not look bad at all. The thing that wears really quickly on that finish on pistols is the grip frame because of the constant friction from your hands, plus the salts from the hands. A lot of people like the patina that develops there. Of course, mine have brass gripframes so no wear there!
I wouldn't hesitate to buy charcoal blue. A lot of reenactors buy it so they can rub off the finish easier to make their guns look more used.