I made this Dredged Leather farming guide to help out players who want to farm the leathers instead of buying them from the Auction House. I traveled around Nazjatar to search for places with high density of mobs which I can kill and drop Dredged Leather. Below you will find a list of places I think are the best for farming Dredged Leather.
Dredged Leather ranks
The rank 1 requires Skinning 140. You can learn it from your trainer Rolm / Instructor Ulooaka at Nazjatar. (You have to finish the first few intro quest at Nazjatar before you can see these NPCs.) You can still skin the mobs without getting the rank 1, but you will get fewer leathers.
You can get the rank 2 from Vor'koth. To summon him, you have to loot a Chum from beasts at Nazjatar. (random drop) Then toss the Chum into the Eel Infested Water at this location. (Coordinates: 48.35 24.31) Kill the 3 mobs that spawn, loot the chum then throw them in again. Repeat this several times then Vor'koth will spaw. It's a rare mobs so you might not be able to solo him if you have bad gear.
Both the Rank 2 - Skinning Technique: Dredged Leather and the Rank 2 - Skinning Technique: Cragscale are dropped by him, so I had to kill him twice to get both recipes because I could only loot one of them from one kill.
Rank 3 is from a quest item that drops from Skinning Dredged Leather. (random drop, not 100%)
Nazjatar - 1
There are all kinds of Snapdragons around the marked area, all of them drop Dredged Leather (except the baby snapdragons). A lot of them are elites, but they are pretty easy to kill if you have decent gear.
If you haven't finished the Snap Back quest, then you should pick it up from Collector Kojo. You will get a scroll from the quest that allows you to kill Elite Snapdragons much faster. So if you don't turn in the quest, you can drastically increase your skinning rate.
Nazjatar - 2
When you first go to this area, there will be a lot of Nagas there, but once you kill all of them, they won't respawn as fast as the Savage Snapdragon. It seems there is always at least 3-4 Savage Snapdragon at this area, so once you cleared the Nagas there will be mostly Snapdragons there. They are a bit spread apart so you have to move a lot, but this is the only other place where you can get Dredged leather.