Unless they are found camping some location, the Nachs leave only their teeth, which are worth so little that they’re unlikely to even cover the cost of ammunition spent and equipment repairs needed after the fight. I find it odd, especially after the overhaul which made them potentially lethal opponents. Even wolf pelts are worth more (both in coins and for crafting), and all other humanoids are bound to drop something useful.
So, can we get some additional incentive to pick fights with them? Right now I mostly leave them be unless I’m either actively hunting for exp or needing to stop them from eating someone who I’d rather keep intact.