Goblin description says they are "A medium-sized humanoid driven to cruelty by its evil nature." Thus we can safely say goblins enjoy inflicting pain,agony,etc on their enemies.We can also gather goblins are smart, they can built towers of slade and forge weapons, they also have a language unlike kobolds. Wouldn't it come to mind even if they ARE evil creatures that they would not band together because a group can over power others(birds of a feather flock together)? Another thought to this argument would be if they are driven to violence would it not be a pack mentality where the strongest becomes the leader? A demon would certainly be able to kill many goblins(aside from the lucky ones) thus becoming "pack leader", the alpha goblin as it were.
But this contradicts there lore, toady himself has stated that goblins don't like other goblins, so why would they band together with other goblins they don't like for purposes other then the occasional mating act? People form societies in fear of hunger, thirst, and ultimately death, but a goblin has no need to worry about any of these things(unless he gets murdered, in which he'll most likely have a higher life expectancy by not being in a goblin settlement ).
They should should all just be acting like night trolls and kidnap and kill people without a civ backing them up. A sentient creature truly evil wouldn't bother wasting it's unending life to feed the evil agenda of others, but instead go with his own agenda. They should be total anarchist ,because they don't really need a civ to live.
If I was a creature who didn't need to eat , drink, and could live forever I wouldn't bother getting a getting an occupation and contribute to the community. In fact if I may be so bold I would recede from society and I would just walk the earth and do "WHAT I WANT, WHEN I WANT, AND HOW I WANT IT". Big red would not be enough to deter me from going out on my own, he could be satan himself and I'd still give him the green middle finger. I mean what can he do to me that won't happen if I stay anyway? He's got nothing to threaten me with because I'll be killed if I stay anyway, either by the hands of another goblin or on a suicide siege on Uristmctraplover's fortress.