Well, smoke genasi tend toward the lazy and occasionally the crude. The tend to be tall and lanky, with dark skin and hair. Like other genasi they also have one or more other unusual traits like hair that billows like smoke, a faint smoke-scent around them all the time, or a faint haze that clings to them. The smoke cloud they can create is like the smoke cloud created by the pyrotechnics spell, though you don't have to have an open flame to do it. You use it as a sorcerer of your character level. Your racial bonus vs. cloud-like spells is +1 per every five levels, and is good against things like stinking cloud and cloudkill.
You tend to see smoke genasi in large cities (like Andeluvay, the capital, Albon, the biggest free trade city, or any of the port cities) where there is plenty of smoke, though occasionally you find some further south near the volcanic Firespine mountains.