Always.
At he moment my players are facing, what are essentially, Somali pirate dorfs.
Skin colour varies on where they travel, obviously they meet travellers of varying skin tones and races.
Funny story was that in the beginning, every time i would mention someone had a different skin tone, the players would befriend them and follow them around thinking it was a plot hook. They bothered a poor old dark skinned fellow at a fruit stall for several days once (They had been sent to a small town to find a "unique looking gentleman", it was actually a halfling pimp coated in body piercings they were supposed to latch onto).