Would it kill AirBnB to do random (or even algorithmically-determined) audits? Auditor signs up for a night in your house. Let's say your listing has fake pictures or fake amenities. Or you try to bait and switch the auditor by having them stay in some crappy other property because the main listing "is having plumbing problems". Bam, audit failed, your account is frozen, your listings are removed, and you are banned…
I'm totally down for these audits, but expect the auditor to pay the fee like anyone else if he/she stays, or if he/she consumes the timeslot that I could have sold to someone else.