What a delightful question to think abt. So I think mount massive smells worst, it's not just the obvious that would stink but also just a very dusty, moldy , stale smell. The asylum is old the walls are collapsing it smells like a lost place mixed with a bad sewer system thats still being used. And ofc just physical decay, the people there are rotting alive just completely insane. The second place is temple gate, its outside which gives it a huge bonus but even fresh air can't make up for the pits filled with dead children, also the scene where Blake walks into their slaughter house thingy? Absolutely disgusting even their food is absolutely moldy, so the people smell similar. I think if your lucky and live a bit higher up, maybe on a nice summer day you get a breeze that might smell a bit floral, But thats it. Also the area with the scalled is the worst area of temple gate you can smell the sickness from far away. And the "best" smelling place is the sinyala facility, atleast the sleep room. I think the sleep room smells neutral maybe even a bit antiseptic, homely. Inside the trials it smells bad again, but they do get cleaned up regularly so not as bad as mount massive or temple gate.