I sold my house in the US.
You don't stay for viewings there. The potential buyers are accompanied by their own agent, and your door key is in a lock box attached to your front door, with swipe card access by certified RE agents only. Viewings are usually arranged only a day in advance at most -- you could get a call from your selling agent asking if you could clear out and let people in in an hour's time. I never turned down a request for a viewing.
Properties for sale were expected to be in pristine condition. We used to dash around and put things away everywhere we could bung them if we were pressed for time pots of dinner into the oven and microwave and even into the dishwasher sometimes and we sometimes decamped to the car with our dinner plates with us. We often ran out the back door as the viewers were coming in the front. Every light was turned on, doors opened, heat turned up (it was winter), cat cautioned to be on her best behaviour... I kept the place like a show house for the weeks it was on the market.
Viewing slots are an hour long where I lived. We once returned to the house and had just taken off our coats when the people who had booked the viewing showed up having missed their hour, and exH turned up to collect the DCs for his weekend at that moment too. I got the DCs' weekend bags, said goodbye to them, and off I went again and just sat in the car until I saw the viewing party had gone. Later, exH berated me for arranging a viewing for the time he normally picked up the DCs 
-- don't know why he felt it was important to have the front porch all to himself but heyho.
My neighbour's house failed to sell. My agent had heard horror stories about it from viewing agents -- food left around, beds unmade, clutter, children's toys, floaters left in the loo, bath with a noticeable ring around it, half eaten sandwiches on the floor, dirty laundry in a pile in the basement, poorly done DIY and 'decorative' painting effects.
When I was touring around looking at houses myself, my agent and I once found a teenager sleeping on a mattress in an attic bedroom in a house that was supposedly empty. We also found a house where the only thing in the kitchen was a big kitchen sink and a TV dinner tray piled high with dirty dishes. I don't know who ate there, or what they ate.. Another very sad and offputting one was a lovely big house that hadn't been redecorated for at least four decades, garden hopelessly overgrown, where the kitchen sink and the bin were overflowing with booze bottles and the bathrooms were pretty much destroyed, nothing to eat in the cupboards but plenty of liquor. It smelled like a pub, and despair.