I've run into a scam recently on AirBNB and several situations that ended up screwing me over. The scam was after booking a nice place in Orlando, Florida for a week through my wife's AirBNB account. The day after booking, the "owner" sent an email saying that they required a photograph of the front and back of her credit card, drivers license picture and full name. Not even a subtle scam, but that would probably fool most people. After contacting AirBNB support(which is a difficult task itself, good luck finding a form), they took 3 days to respond and responded with a "yeah, don't send them that. Sorry". Of course, the listing is still there now when I look.
I've also booked trips to Tokyo and LA recently, and in each place the reservation was accepted, payment was made, and 2 weeks before I was set to stay there, the owner canceled the stay. Why? Doesn't matter, the owner can cancel without penalty for "unforeseen circumstances". Of course the renter gets charged a massive fee for canceling including, naturally, AirBNB's fees.
My fraud alert is always on high now when using AirBNB and I think no one should put all their vacation eggs in the 1 basket with them. Too unreliable, too flaky on reservations, and too we-don't-care-about-you attitude towards the renters.