Not sure Petri, but from what I've read, in some cases I guess they are fine, if still illegal. But in many, they are scams, or reported by neighbors and people are evicted. There are legitimate apartment-style hotels like the Beacon above or Affinia properties.
Perhaps one of the NYC residents can weigh in. I am just a frequent visitor, but I can certainly understand and respect why these laws are in place. Housing in NYC is incredibly expensive, and if owners or brokers can rent apartments at hotel rates, more people will get priced out of the already tight market. And I for one would not want to have a revolving-door rental next door to my place, even if the visitors are as nice as you!
oh, and with airbnb, owners are supposed to be there when you stay, which is allowable under the law, ie "couch surfing."