Airbnb is a great vehicle for connecting well-intentioned and responsible travelers with hosts, until it's not. Here's a situation that Ari Teman never throught he'd be in. Friday night, in a seemingly normal transaction, he rented his Manhattan pad to a guy who was just looking for a place for his relatives to stay while in NYC for a wedding. Nope. When he unexpectedly returned to his apartment that evening, he discovered that his tenant was hosting a, well, as twitter put it, a "XXX Freak Fest." Uh oh.