You would also find that Toady has flat out stated that this is the one area of detail he will never ever touch. He's not going to make dwarf poop, he's not going to make the player deal with it. It's just not going to happen.
What the heck, he's never said that, at least not that I've seen. Here's what I could find on the topic:
There are no plans to add "night soil". Dwarves poop little pebbles which seemlessly disappear into the cavern floor, or they collect them and cherish them or something.
[topic: "Livestock improvements"]
4. Manure, as a fertilizer.
4. They just drop it everywhere? Everyone will might be doing it after a while... night soil, and so on. But it's a dangerous door to open, especially if the room on the other side is full. If a god turns you into a horse in adventure mode, would you suddenly start dropping the bomb?
Note the dates. I think he also once said in an interview or something that he'd only be interested in adding it if it was a fun element of the game.
As for sewers themselves, he's definitely positive about adding
those:# PowerGoal153, THE CRACKS OF DOOM, (Future): You flee into the sewer with the baron's ring, but sliding in the muck, you drop it. Try as you might, you cannot locate the precious object in the town's filth.
And finally, it's worth noting that shit and piss are already in the game. Everyone who's encountered tentacle demons has probably discovered this for themselves, and
Toady confirmed it recently:Rainseeker: [1e.4]So there's no poo creatures either?
Toady: It was a close thing! Because it was literally a decision I had to make, going down this list, because in the Hidden Fun Stuff of course if you get the tentacle demons then you get a layer scattered with various filth on the ground; and there's brown filth and yellow filth and so on and it's not clearly stated but it's a material that I had to put in properties for right? So there's these hard-coded filth materials, and when I was going down the list, you know 'Do I want creatures made out of mud? Do I want creatures made out of vomit? Do I want creatures made out of glass?', there's all these hard-coded materials, and I was just like 'Yeah, yeah, yeah ... No ... No ...' on the filth. But there are creatures made out of the grime, and the grime material is the material that collects on your body slowly over time, and it's also the material that's used in swamp water, so there's this ... I just needed this material called 'grime' for these miscellaneous purposes, it's just crap, just stuff that collects over time and when a creature is made out of that it just says 'composed of grime and filth'. So if you want to call that 'poo' even though it's not it's possible for you to extend your imagination.