They're bearable when the wind is in their sails; they can even be crueler than their orc masters. But let a little adversity blow their way, and you'll see those piss-poor troops crumble in minutes.
It's this very nature that doomed them to a life at the bottom of Green Skin society. They're content with their lot, assuming all the responsibilities the orcs disdain—which essentially means everything but fighting.
Sometimes, when the orcs felt gloomy, they would snatch a few of those cowards to eat and lighten their mood.
These cowards weren't particularly good as industrial workers or farmers either. Their cunning would show up in their work, as they loved to cut corners and cheat. But this problem was somewhat easy to solve: the orcs would personally wield whips to supervise, or appoint a favored coward to do so. The latter could be even harsher on their own kind than the orc masters.
Through these means, Green Skin society maintained at least a minimal level of productivity.
