My toon on Smolderthorn does not make much money selling on the AH, but I am a very hands off guy, and never feel like shouting in cities for business.
Smolderthorn is a new server, and there are a good number of leatherworkers at the same level as me. However, I didn't begin LW to make money, but to always have up to date gear for myself and my other leather wearing friends.
On Burning Blade, I have a 20 rogue / 150 Lw, and he can sell items on the AH pretty well. Whether people just buy to disenchant, or to actually use, I dont know, but I was able to level to 150 hardly selling anything to the vendor.
As far as what other classes make money, I had good luck as an alchemist on Burning Blade too. My mage had enough for his mount by 34 by just selling potions. Maybe pvp servers have a higher demand for potions.
I will say that I never bought materials off of the AH, but gathered them myself. It is possible that the raw materials would sell for more, but I did okay selling finished goods.