Usually, as history goes, every deed considered morally evil done by a member of the races forming the Horde is unequivocally attached to the Horde itself.
If Garrosh creates so much of a different Horde to give it a different name, kicks you out, and you have to start a Civil War over it, it's still Horde.
If the Queen of the Elves calls Sargeras to Azeroth because she wants his children (for real), then it doesn't count because "that wasn't the alliance yet" or "but she acted independently".
Human Mage Kel'Thuzad and Human Paladin Arthas also were not alliance, just some renegades acting on their own, while Putress at the Wrathgate was "Horde".
The Cult of the Damned might be comprised for 99% of Alliance races only, that still doesn't make it an Alliance evil deed, obviously!
The leader of the Church of Light being the 2nd in command of the Twilight Hammer also casts absolutely no bad light on the Alliance, yet another independent madman, unlike the orcs, it doesn't matter if they were deceived into drinking demon blood, it's still their fault.
Gul'Dan is the orc with a demon as his master and proceeds to deceive an entire faction into destruction? Horde!
Medivh is the human with a demon as his master and proceeds to deceive an entire faction into destruction? Neutral character!
The de-facto co-leader of the Night Elves in the ever-lasting absence of both Malfurion and Cenarius, Fandral Staghelm, being the leader of the Druids of the Flame, an elven cult, and 2nd in command of Ragnaros, is also yet another independent act completely detached from anything remotely alliance and for which the alliance deserves no critique, not like draenor orcs! deceived by eredar leaders? made drink demon blood? excuses! it's an evil act of the Horde!
Daelin Proudmoore racist war on Durotar was a misunderstanding, so was the purging of Dalaran and Garithos attempted genocide of the blood elves.