The warehouse in the capital was completely empty. Nothing in there but sand. I would've enjoyed shopping this big a city if it weren't for the terrible lag. So I did my shopping overland, jogging instead of fast traveling to collect my leather from the wild. I want to get speedy enough at tanning and leatherworking to quickly craft a full set of werelizard-sized leather armor before hunting. I don't really need it, but the Poet needs to improve her Armor skill in order to wear metal armor.
I came upon a small burrowed out hill with a door, vacant. I spent about 1 1/2 day there, expanding the lair with downstairs workshops and a beer pavilion on top, turned all my skins into leather armor and wrote a poem. There should've been 5 moon horrors in residence here, but no one showed up. I searched histories and the only one I can account for was shot by a marksdwarf in the surrounding region. I haven't seen a single dwarf anywhere near this civ! Where is this guy, I need to recruit him!
Later I ran into evil lands again; I knew from rumor it was around there somewhere, but it wasn't at all obvious from the world or fast travel maps. I saw and glumprong and walked toward it, and suddenly I was leaving a vivid purple trail. Repellent muck was falling from the sky, but it combined with normal rain to wash off on contact. I didn't get any emotion from it, and no symptoms have appeared, so it either it didn't have a contact effect or it was too diluted with water to be effective. The only evil denizens I encountered were harpies, and while they were funner than fighting vultures, their skins couldn't be tanned. I would've liked some beak dog leather.
The underground populations pouring up into the keeps was a bug fixed in 42.05 though. Did you update and see if it keeps happening?
Not yet, but I'll probably do that before seeing another human civ. But like I said, this is the third 42.04 world I've genned, and it didn't occur at all in previous cities. If it's a bug, it's not a common one, and not a game-breaker imo.