It's funny you should mention this, because I think that has happened to us recently. I'm certain we did not have Instant Book switched on - in fact sure of it - because we declined a month booking for six 19-20 students for our listing on the basis that it was just not a good fit for a treasured family house. Then a day or two later, woke up to a number of bookings having been auto accepted overnight! Now we face a visitor and 3 friends arriving who I have reservations about because she has no profile or reviews and has not supplied any information about the kind of people they are.
I think I have to stop reading this forum! Some of the stories and issues have me worried before we've even started! I would, however, be interested to know if others have had the same experience.