what is the story with brooklyn landlords constantly knocking on the door and dropping in for no reason as if you aren't paying them rent for the space.  i have never experienced these interruptions in any other city. 

If you are a subsidized tenant, meaning your rent is paid in full/part by a governemental agency, the landlords have a duty to the city regulators to "maintain" the apartment. Which means constant check ups/visits to your apartment.

If not, then your landlord is violating your tenants rights, and you need to file a formal protest with the local courts.