4x tailors here with the skill...

At first I thought it didn't matter who had the skill. I started with only 2 of my tailors having it. Then I leveled the other 2, picked it up and saw the difference. I keep loot on FFA so I haven't tested any other way, but it appears that every tailor has a chance to get extra cloth. I say this because when I had only 2 tailors with the skill I would loot 3-5 extra cloth max. Now with all 4 tailors having it I loot 4-7 extra cloth.

I am assuming it adds up all the tailors cloth and puts it into 1 loot table when it's on FFA. Otherwise, I bet each tailor would have 1-3 extra cloth each on group loot (I am going to test this soon).

I loot everything with my Paladin, then I look on any of the alt screens to check for glowies. I can then only loot one time on any of the casters, and it's usually a nice chunk of cloth (I averaged 5-7 extra on every pull in the Nexus). And this is above and beyond whatever the Pally gets on the mob's base loot table.

It is a very nice tailoring ability and I am glad I picked it up on all 4 casters. It will help level them up quickly, as well as first aid.

Edit: You can train this at I think 350 Tailoring from your trainer. Otherwise, you can loot this book A Guide to Northern Cloth Scavenging, which can be used at 325 Tailoring. My first two tailors learned it from the trainer, and my 2nd two got the book from killing Scarlet mobs in New Hearthglen. The book drops for the entire group, but only shows for tailors.