> If the host really needs to cancel they should have to put the traveler in a real hotel as an upgrade to remove all doubt of the traveler getting into a place that could be worse. They have already received the money from the traveler so they only need to pay for the difference.
New scam: post a listing for a very high-end place you don't own, cancel the booking once you've been paid and book the client a cheap hotel, and pocket the difference