Kill the Jadefires/Satyrs in Dire Maul East. Use the entrance at the circular buildling north and slightly east of the horde camp in felaras which takes you to these creatures straight away instead of the entrance in Dire Maul. Fel cloth drops off just about everything else too, at a similar low rate. I did a farming run killing the bosses and any mobs in the way and got 5 fel cloth from about 1 hour as an epic geared level 70 warlock. Pity on my realm felcloth is worth little.