I have an 07 Black GGH Day, 08 Black Messenger and an 09 Black City Special with pod. They all are still very black. I have used my black City the most and it is very black and I live in the high altitude of Colorado. I even have left it in the sun at my Kitchen table through the days and it is still black, black. I haven't ever put any Apple care product on any of my Bals because I think it changes the color of leather. It did on my LV vachetta leather.
I wonder how many tPF's have used Apple Care on their black bags. It would be interesting to know. I noticed that one gal that wrote about her bag turning had put AG on hers just after she got it.