The welcome mat before the door is a flat but necessary gesture. There’s no accounting for what people might drag in on their shoes: dirty politics, forgotten manners, previously owned opinions. It’s best to have your so-called guests just leave it there out front, before your door. Hand them a receipt, if you must. Make sure they wipe their soles until they’re clean enough to eat off. Discourage feet on coffee tables, ottomans, and children. Make sure they use the footprints that you’ve fixed onto the floor. Post penalties for failure to comply (I suggest large font and bold) in conspicuous places where guests most likely linger: living rooms, bathrooms, closets. And when they leave — if they leave — be sure they know what’s theirs. Be gracious in your own way. They’ll say “Thank you!” Say “You’re welcome!” Then close the door, and lock it, and pretend that you’re at home.