It really seems to depend on the city. For about $100/night in Zurich I stayed once in a huge top floor flat and once in a bedroom with private bath in a giant palace with plenty of room to entertain dozens, which I did. My company's negotiated hotel rate was $425/night and I pocketed the balance.
In NYC all of the Airbnb inventory is bedbug-ridden hovels. Perhaps this simply reflects the housing stock of the region.