Rifle brass, I'll pay a little more or "clean" brass off the ground, I'll take "dirty" but the price better be right since it'll dirty up my media and take longer to clean. Also, if it's being sold by weight, the price needs to drop if it's dirty, not willing to pay "brass" prices for the dirt that got swept up with it.
Pistol brass, I prefer to buy tumbled, I have tons of dirty range pick-up handgun brass, so it's nice to buy pre-tumbled for when I need to load 500 rounds for a weekend really quick and don't have time to tumble my own. I will not buy crimped primer handgun brass, and when I randomly find it, it gets scrapped, too much work.