That way they know who to spit on, right? Helps us, too.

What would them humans think if they came to Dust Town and saw how the rest of us really lived? The ones that are casteless, the ones who aren't even considered worthy of being servants in the homes of the wealthy or pure enough to work the forges in the Shaperate? The nobles make sure we casteless get tattooed so they know who we are when they see us. Proud, noble warriors who like nothing better than to mine a vein of ore or forge a decent sword. It isn't even just the humans, there's surface dwarves who're born and bred up in the sun who think the same things, don't know any different. Point is, he tells me what them cloudheads think of us dwarves down here. Who am I to argue when someone has an angle? How he gets let back into Orzammar I can't rightly say… he claims that he has a deal worked out.

“ There was a merchant come by Dust Town the other day, some poor sod who's had his skin burnt by the sun up on the surface lands once too often, I'd say.

Dwarf dragon age origins