1. No good deed goes unpunished. Frequently folks post on here about trying to "convert" or "help" their friends with BBB and it's not gone well. Without spending quality time on this forum reading the threads, it's hard to get folks to "buy in". It's VERY rewarding to get someone engaged, talking and asking questions, but the more common reaction is a polite, vacant stare.
2. Copper stains are one of the most mis-diagnosed ailments. They certainly exist but in rarer instances than people think. Copper staining is normally VERY dark blue, maybe almost black.
3. Chem gurus help me out here but I believe ascorbic acid is primarily for treating iron stains and while it is VERY effective for that, it may have little or no affect on the stain if it is indeed copper.
4. I may get busted for #3 above but that's what I seem to remember......just not sure it's a fact.