It's usually seems like 75% of some kind of loot you can't use.
I am shocked! wih 4 armor types and only 1 being useful...75% seems ... yeah...
Well myself + my guilds holy pally have only seen 1 spirit plate drop from ~40 heroic 5mans. I can understand why people get fustrated with RNG.
(also we haven't seen rng like this in a long time, in wrath/cata you just bought rep gear/badge gear until you got what you needed -- now its just "farm more")