As an individual who admires energy, tenacity, courage and faithfulness, I believe Ugluk of Isengard (introduced in The Two Towers) has more than "mildly positive traits." A captain of the fighting Uruk-hai, he commands a troop of orcs that capture the hobbits Merry and Pippin, bringing them partway to Isengard before he is killed by horsemen from Rohan. Ugluk fiercely demonstrates and promotes a clear set of values that include bravery, determination and loyalty, all of which are VERY positive traits.
On courage:
"I don't trust you little swine. You've no guts outside your own sties."
Yet he does seem to trust—and gladly reward—those he identifies as sharing his warrior spirit:
"We are the fighters. We'll feast on horseflesh yet, or something better."
In fact, Ugluk's group loyalty is so strong, he introduces his troops as being "servants of Saruman the Wise, the White Hand" before he introduces himself by name. Even under duress, it remains steadfast. When "the [enemy] horsemen had encircled" his group and are about to go in for the kill, Ugluk keeps his mission in the forefront of his mind, at great danger to himself:
"Put those Halflings down...as long as I'm alive, I want 'em. But they're not to cry out, and they're not to be rescued."
At the very end of his life, he is apparently in the "one band, holding together in a black wedge, [that] drove forward resolutely" rather than abandoning his comrades.
Ugluk also compares favorably to the "good" characters, particularly Hobbits, in his willingness to place personal accomplishment ahead of physical comfort. While he does show consideration that his "lads are tired of lugging you [Hobbits] about," he will readily "march day and night" through dangerous territory and "leg it double quick" when being chased by riders. Even with the fate of the world at stake, none of the "good" characters show this sense of urgency. Describing Ugluk's journey, the wizard Gandalf admits:
"So between them our enemies have contrived...to bring Merry and Pippin with marvellous speed...to Fangorn, where otherwise they would never have come at all!" (emphasis mine)
Ugluk would probably have no way to know the exact purpose of his mission, although he is aware the hobbits have "something that's wanted for the War." Given that he was presumably raised in Isengard with scant information about Middle-earth's geopolitics available, his ignorance that Saruman was an "evil" faction would be quite reasonable. Thus, his capacity for "good" in the canonical sense is somewhat untested. However, Ugluk is able to respect skilled fighters beyond his own race and even beyond the dark factions. He describes Boromir as a "great warrior."
Furthermore, his discipline in keeping the Hobbits "alive and as captured" throughout his march suggests that under a different training regimen, he might even be capable of observing and fiercely enforcing the 7 principles of Leave No Trace outdoor ethics, which protect ferocious predators and stately trees alike. https://lnt.org/learn/7-principles. Although circumstances are causing the orcs of Isengard to cut the local trees, it is not inherent in all orcs to destroy forests on sight. In The Hobbit, we see that the Misty Mountains orcs not only frequent an apparently sustainable forest near their homeland, but are allied with its wolf inhabitants.
Keep in mind that The Silmarillion was ostensibly written by the orcs' elven arch-enemies and the scene in which Ugluk appears was written from the perspective of hobbits, Middle-earth's most comfort-loving race. Hobbits would be unlikely to identify any of Ugluk's qualities as positive because such qualities are practically the antithesis of their own values. The Ents, who pride themselves on their ponderousness and look down on anything "hasty," would also be contemptuous of the orcs' love of swiftness. However, other enemies of orcs react differently. After observing Ugluk in battle, the Rohirric commander Eomer considers him a worthy opponent to dismount for and fight man to man, sword to sword.
In short, the characterization of this orc always made me skeptical of the blanket policy of killing orcs on sight, especially in peacetime.