What authority does a landlord have to allow a police officer to enter a living room?

It seems to me unreasonable for a police officer to assume that, merely because the landlord gives him a key, he can barge into a living area, albeit one shared by other tenants. A warrantless search is an exception, Schneckloth v. Bustamonte, 412 U.S. 218, 219, 93 S.Ct. 2041, 2043, 36 L.Ed.2d 854 (1973), and the police should start out with that principle in mind. When the police receive a landlord's consent to enter an apartment or a living area shared with other tenants, they should be under a duty to inquire regarding the authority of the landlord. Under the circumstances of this case, I just do not believe that the police acted under a reasonable belief of proper consent when they proceeded into the kitchen and then into the bedroom of this dwelling house. The police should not be encouraged to rely upon an open-ended, non-specific consent given by a landlord with dubious authority to authorize an invasion of the type described here.