We've just had a guest who experienced precisely this.
Apparently, they booked a place long ago, but it was a fake. Somewhere between the time they booked it and their arrival, Airbnb caught it and took the listing down.
However, Airbnb failed to inform the guest who had booked it, and the guest showed up at the house at check in time, only to discover that it was a fake listing.
On the bright side, apparently Airbnb paid hotel rooms for the guests and eventually booked our listing (we had just received a last minute cancellation due to a family issue) and paid for that too. Good on you, Airbnb!
So, while Airbnb made good on all of it, their negligence in informing the guest caused some serious frustration for the guest, and all could have been avoided, simply by promptly informing the guest that the listing had been removed and giving them a refund.
It seems these fake listings are becoming all too common. I found two last month in our area, both from the same fake owner, the telltale sign was that the first lines they printed in the description was that "due to overwhelming demand, guests must contact the host by email or WhatsApp before they can book it". These listings lasted nearly a week before being removed. No telling how many people booked them. Or how many have yet to find out they were scammed.
This is not good for Airbnb, its guests or its hosts. Everybody loses.
So, if you see a listing that appears fake or dodgy, it's important to report it immediately. It can take Airbnb quite some time to get around to it.