To me this sounds like the work of meth addicts (I have another post on the thread about this), but I do share your general suspicions.

All of a sudden AirBnB seems like a tough brand to keep clean -- at any time a host or guest (or frankly anyone) can either do something crazy or fabricate a story about doing something crazy.

I have very few tools at my disposal to verify these claims as a passive observer, so the net result is to trust the AirBnB system less.