It doesn't take much! A shoe in the middle of a hallway makes it slightly more trouble to move past without tripping, or a box under a desk makes it slightly harder to vacuum. Over the course of cleaning, each time you think about something like that is a small source of stress that makes the task less pleasant.
It's the same thing in a codebase. If your functions mutate arguments, even a little, or if the code is not formatted consistently, the resistance to movement increases, and tasks become less pleasant. If you wait for real spaghetti code it's already too late; if you're used to chaotic code, you won't understand what I'm talking about.
I love the comparison to codebases. I just wish I could commit the perfect tidy version of the room to a git repo and then reset to that every night. :)
If you have kids it takes about an hour for the house to become hard to move around. We're taking about tiny pieces of lego all over the place, cars building blocks, train sets etc