Oh man... This reminds me... I lived in an apartment building for a while and the downstairs neighbors were always complaining about stuff falling down from our balcony to theirs, or rain water dripping onto their laundry, or cooking smells, or noise... I can only imagine chicken poop sludge dripping on somebody's stuff or the noise complaints! The thing with apartment buildings is that, with so many people crammed in them, it's extremely unlikely you'll get along with everybody. There will always be that one person who will complain about everything, and chickens will just give them SO many more reasons to complain, or even get you kicked out!
I live in a house with no houses on either side. There’s two houses across the street, and a few trailer/houses diagonal and going up the street. My yard is large, the houses going up the street have large yards, and one of the houses across the street has a large yard. My chickens free range, and visit their yards.
I have never had a conversation with any of my neighbors. (I’m a bit of an introvert) I leave cartons of eggs on my neighbors porches (as a “sorry for my dumb birds”) and they leave empty egg cartons on my porch (presumably meaning “it’s aight”) if anyone has complained, they haven’t complained to me, so I assume it’s alright.
everyone on my street has a house, and can get away from the smell (which I’m pretty sure only exists in my yard, but I do try and get a good sniff from the street just to be sure) noise, and general mayhem of my chickens. The guineas not so much, but if anyone complains to me about them they’re SOL because guineas are a-holes... in an apartment situation I’m certain my chickens would make it three days tops. An apartment is unlike a house because at 11 stories up, it’s not like you can just chase the chickens to the other side of your yard. Apartments, from what I’ve heard, can be pretty cramped and stuffy. I wouldn’t make someone, on top of living in an apartment, live in an apartment with chickens on the porch next door/upstairs. i wouldn’t want to live in an apartment with chickens on my porch, either.
and the more I think about it, the more I’m convinced that’s gotta be a health code violation or a biohazard or something. I think there’s a rule about dealing with livestock waste and preventing runoff. Seems like something the CDC would be keeping an eye on. Especially with the coronavirus concerns going on right now, I wouldn’t consider keeping livestock/poultry within a city.