All Airbnb has to do is post notification on their website that many cities now require permitting for short term rentals. As I use the service when I travel, I've noticed a photo of the permit included with some of the rentals. It implies, if you rent a unit that doesn't include the permit, there is a possibility the rental could be shut down before you arrive. Put the onus on the buyer.

On another note, after some experience with Airbnb in our strata, we created a bylaw to deal with it and they were shut down. The most recent was actually a renter who was subletting to vacationers via Airbnb, while she stayed with her boyfriend.