To me, the big decider is plush carpets. The first level of my house is mostly hardwood and tile. The second floor, and living rooms have plush carpets. So if someone is unloading a car, getting ready to leave, or just general in/out stuff, sure leave the shoes on. Once you’ve decided to stay, get those shoes off and be welcome in the cozy areas of the house.

Which, coincidentally, is also the areas where other warm stuff is.