Even if i love the Horde, between the 2 factions, they are the most questionable, even if you only limit yourself on how they act regardless of war.
Orcs: Abuse the workforce (peons)
Goblins: Extreme capitalist that do not care much about... well... anything or anyone but money (though it may change a little with Gazlowe as the leader)
Forsaken: Human experimentation
Blood Elf: Dubious experimentation and consumption
Trolls: Cannibalism
Zandalari: Classists
Maghar Orcs: Some are ok, others are not (as they do have a clan of sadist with them)
Taurens are the big exception to the whole Horde questionable practices and Nightborne (but those guys haven't had the chance to do much)