So far no coppering on the males: none on the nasty one or the sweet blue roo that got taken by the hawk. The black male is all black and my black female is all black not a copper hair on their hides lol :D I really need to do more breeding but they are supposed to be all true blues. I had a blue line earlier that had some coppering show up on a male but I am really thinking it was from the sun now because he got the dirty brown tint on his saddles like even my pure blue ameraucanas get after running around in the FL sun all summer long. After this particular guy molted, he was all nice solid blue again sooooo... I didn't use him for breeding though because he also has middle toe feathers and they are too much trouble to try to breed out. I've had too many projects and things going on (not chickens lol) and haven't had much time all throughout last fall and winter to work on my chicken projects so hopefully, I can do some this spring and summer.
Like you, I would not want someone to sell me the wrong varieties by accident or worse yet, intentionally. I will not sell eggs from the blues or blacks until I know for sure:
a) they don't have any coppering, b) combs look good (no serrations like on the black male) c) egg color is superior d) shanks are feathered correctly, good tail set, etc. This could take awhile LOL! Once you think you have something down, something else pops up. I had thought, Wow! I got a black male I like his shanks and tail set and build....hmmm maybe I'll show him...then his comb got that double serration haha good joke on me.