A lot of people half-ass the transition from outside to in and would step with a socked/bare foot right where they just walked with shoes. Meaning the isolation of in and outside dirt is broken. My roommate, the landlord, does this… I’m not gonna chase him around with sanitizer and a mop so, I see the floor being just as dirty as outside and wear socks and slippers all the time. (They also ignore the idea of cleaning or maintaining their house. But that’s another issue and a reason I’m looking for me for a 1br)