I have been skinning [Mudrock Spikeshell] in Dustwallow Marsh (on Lordaeron), but some times roughly 1/3 or 1/4 of the times I skin them, the (skinning) loot window shows up empty. I cant recall that I ever had a skinning action yield no leather or other item before, but I could be mistaken.
Is this a bug or is it an intentional game mechanic?