It's a matter of world building. Orcs can be noble savages, or violent monsters. The main problem is humanizing these creatures. If you instead imagine a separate evolutionary path, then the race can be inherently "evil".
If orcs have evolved for conflict and violence far beyond human levels, then by our standards they would be evil. At least by the philosophy of a middle ages like world. Catholics and Protestants considered each other evil for a few hundred years. A violent species that destroys humans on sight due to their violent instincts would easily be evil. Exceptions could exist, but the mass of individuals would be "evil".
Just listened to the Empire podcast about Catherine the great. Turns out the twat she was married to was the kinda idiot that managed to get everyone against him, so when the two came to blows everyone he tried to recruit was already sworn to her. Didn't go well for him. Then Catherine's son was exactly the same as his father and when she died, his own children joined in on the coup against him. The point being, if you piss off everyone by being an absolute ass, then their dislike of you will force them to join forces against you.