Let me tell you a secret, I love brown women.
I like @AutarchYuri was bothered that the tag "very_dark_skin" seems to not really work on some models I use so I reinforced it and also added "dark skin" to my version. The result is that now you can gen 3 different levels of dark skin on most models.
Trigger words: dark_skin, very_dark_skin
Side note: I do take informal requests(basically a bounty that you don't have to pony up buzz for) if I like the idea(Tips are nice but not required since if it's a good idea then I'll get generation Buzz). Just leave a comment on one of my models or DM me. (Comments are preferred since that let's other people see that I'm actually fulfilling informal requests.) DMs are perfectly acceptable if your request is a bit out there and needs some image examples or something.