(recommended for level 80)
head down to shadow fang keep and pull the whole instance to the final boss AoE them all down and loot all greens and all the WOOL cloth (dont take other cloth or the greys or BoP blues unless your enchanter) do this 5 times within the hour and then return to undercity to AH all the greens and cloth greens going for around 1-6g each and cloth going for around 5g a stack (server dependent) i can usualy get 10-20 green items going for around 100g-200g if they all sell and around 10-15 stacks of cloth going for around 50g so that can add up to 250g this is for people without professions i have also gotten an Assasins blade which can go for a lot of money.
Another good instance for farming mainley cloth would be ragefire chasm if your rather low level only kill the troggs and reset but if your level 80 zerg straight too the last boss
this is also a gold mine for lower level green items but the amount of linen is insane. this spot is also close to an auction house so no need for a bank alt
blackfathom deeps may be realy boring but it is also a gold mine for BoE level 15-19 items i got 4 in one run there
as for dead mines stay away its good for cloth but you will struggle to get it too an alt near an auction house without a portable mail box, it is also the most time consuming from start to finish
putting the green items on the auction house is a pain so be prepared to spare some time doing it
DO NOT DE THEM THEY ARE WORTH MORE AS AN ITEM