I have a lvl 58 Hunter with 300 skinning and it brings in some money, but not alot. The only real money might be from killing the elites (Dragonkin, Devilsaurs etc) for the more specialized stuff that sells higher.
Normal Rugged Leather is fast and easy but it only sells for about 10s each on my server and you have to kill lvl 50+ mobs to get it with good regularity. The other leathers sell lower pretty much in proportion to level. They all sell fast mostly, but none sell high.
I havent tried the Devilsaurs yet, but I tried to farm some Blue Dragonscales in Azshara today and the downtime solo farming Dragonkin is pretty horrendous, along with a sluggish drop rate. so I dont think that's a viable gold making option. I'm thinking the case will be similar with the Devilsaurs.
I keep my skinning on the Hunter because he also does leathercraft. Mining and Herbalism will probably pay off better and faster if you are just going for gold. I'm leveling up alts for those myself.