I made this Embersilk Cloth Farming guide to help out players who want to farm the cloths instead of buying them from the Auction House. I decided to search for places with high density of mobs which I can kill and drop 
Embersilk Cloth. I traveled around Azeroth, and after a while I made a list of places.
Embersilk Cloth
Potion of Treasure Finding
Before you start farming, go to the Auction House and buy a 
Potion of Treasure Finding or make one for yourself if you are an Alchemist. With this potion you gain the chance of looting 
Tiny Treasure Chest which contain Embersilk, Volatiles, and gold. Gold is a guaranteed drop, while the other two just have a high drop chance.
Cloth Scavenging for Tailors
Tailors will get a lot more cloth than non-tailors with the 
Cloth Scavenging skill
You can learn this skill by completing the Cloth Scavenging quest, which is given by Charles Worth at Dalaran (Northrend). This NPC exists in Broken Isles Dalaran, too, but he won't teach you Northrend Tailoring.
Cataclysm Classic: You need Tailoring 325 to learn this skill, and you will need Tailoring 400 to get the extra cloth from Cataclysm mobs.
The Bastion of Twilight
This farming place is for Retail WoW players only. If you play Classic, scroll down a bit for the other farming places. But, for retail players, this is the best farming place. They can ignore the rest of the guide. (assuming you have a high-level character)
You cannot farm at The Bastion of Twilight if you don't have a high-level character, so scroll down in the guide to find alternative farming places.
Bastion of Twilight is a level 30 raid instance located near the southwest border of Twilight Highlands. It's on the small island floating at the very top of a tower, you have to fly up to find the entrance (coordinates 34.2, 77.9, high up, link to the exact location). This is the best place to farm Embersilk. You can get around 300-400 clothes every hour. (tailors will get a lot more)
Gather every mob in the marked area, kill them, loot, and run out. Reset the instance by right-clicking over your portrait and clicking "Reset all instances." You can only reset an instance 10 times in an hour.
Don't kill the first boss, or you can't reset the instance!
Deepholm
At the Verlok Stand in Deepholm (roughly around 73, 26), there are Verlok Grubthumper and Verlok Shroomtender on a Pillar up in the air and down below. There are a lot of them, and they spawn very quickly.
Tol Barad Peninsula
The Restless Front is also a decent place, but is often farmed by many players because of daily quests. You will see the Restless Soldier and Restless Infantry bash each other to 19k health, which means it is easy to kill them. The respawn rate is high. You will never run out of them.
Twilight Highlands
Both places have a high density of mobs that respawn fast. You can farm at both places without downtime.
