This is a very well-researched article, which also includes many other popular cities worldwide.
It's important to read all the information, which includes the fact that AirBnB does not "manage" their clients, does not require that the calendars be accurate, and that AirBnB takes no responsibility for clients adhering to local statutes or tax regulations.
If you click on the individual red dots, you can see how many other apartments are listed by the same "owner". Since only a property owner who lives in his apartment full-time has the right to rent it during his vacation time (a period not to exceed 4 months), it's obvious that these apartments are illegal.