Add to the fact that when an Orc razed a Draenei viliage, when they set the entire town on fire, the take the babies and children of the draenei, some of them still clutching to their mother skirt and toss them alive into the fire to burn. Then those that aren't kill are ritualistically sacrificed for more power, carved up on a altar table in front of their kinsmen.
http://forums.worldofwarcraft.com/thread.html?topicId=19110026498Marloke here:

I just thought I would put a bit of a orc response to the above because I am a little shocked at the whole statement and thread.
I am not sure where these Alliance get off asking this from me but here I go:
I took great pride in destroying the Draenei villages, crushing your weak bones, breaking the necks of your women and saving your children for dinner. I did not do it for the burning legion there blood didn't control me. I and I was no tool of theirs. My actions where my own and I only served the one true threat that has ever faced Azeroth. The Elder Shaman Ner'zhul and his student Gul'dan.
You want me to apologize ?
But for what, it was you who invaded our world. You tried to corrupt us into being weak minded fools being controlled by beings of light, loosing our will and honor. You had no right and fought a battle you had no hope of winning.
Unless you didn't notice, we are still at war and I will take great pleasure from removing you from Azeroth in the same way we removed you from our own world. Parts of the horde may have gone soft, our great leaders may be in hiding but the Shadow Council lives on and we continue to make our plans. It be best you sleep with one eye open.