Hi @Ruth199
It works both ways.
The guest pay's in full at the time of booking and the guest could also be paying for flights/car hire etc. That means the guest puts a lot of trust in the host to provide the accommodation booked, and its why hosts are penalised for cancelling a booking.
In 3 yrs with airbnb I have never had a problem getting paid, had no damage done to my property and I have never cancelled a booking. 99% of the time its a very good system.
You read stories on the forum of not being paid or property damaged, but remember airbnb has over 3million properties listed and we only get a small number of people reporting problems on this world wide forum.