Careful with that type of data sharing. It can fail the game theory test. Lets say I'm a selfishly amoral actor in the room rental industry, and I want to lock up the market for myself. I can silence all my competition by releasing blacklist information on a number of current users, then those users will be banned by other sites and forced to continue using my site.

Banks do this today with their info sharing through ChexSystems. I've seen banks that will report their current account holders for the most trivial violations. The result being that the account holder can't open an account anywhere else.