There are no doormen or neighbours,
During its infancy, the Argentine tango found its niche among the less-privileged classes and even among the criminal element of Buenos Aires. This milieu became naturally associated with irreputable and secretive places where afficionados went to enjoy love (in all its aspects), narcotics (mostly cocaine), and tango dancing.
By the second decade of the twentieth century, the more affluent classes of Buenos Aires became infected with the music and its rhythm and sought establishments to enjoy the same pleasures as the other social element but without actually associating with it. This created the perfect environment for secluded establishments such as Corrientes, 348 -- places expensively furnished and decorated and offering anonimity, descretion, love, drugs and tango.
The lack of doormen is rather more difficult to comprehend than the lack of neighbours in that someone had to answer the door when, presumably, a pre-agreed signal or knock was given requesting entry. It is inconceivable that an establishment such as Corrientes, 348, expensively furnished and decorated by Muebleria Maple; where alcoholic beveridges and illegal drugs are sold; where high-end sex trade workers are more or less part and parcel of the overall atmiosphere; would actually have its doors wide open for any passer-by to enter unannounced, or for the manager or owner to answer the door himself whenever a client requests entry. "There are no doormen" must have some hidden meaning -- at the very least, hidden to me. A possibility which must be considered is the fact that César Lenzi was above all else a poet and as such poetic licence -- the artistic above the logical -- was his bread and butter.
The description of Corrientes, 348, particularly the use of the word pisito, brings to mind two possibilities of description: one, that the apartment was part of an apartment building, i.e. a building with a number of apartments on each floor, and, two, a floor in a regular two or three-storey house that had been converted into two or three apartments. In the first instance, no neighbours in very difficult to conceive, but as to the second possibility, one can readily visualize an apartment on the main floor in a house on its own grounds with the owner or manager using the other floor/s as a personal residence; thus, no neighbours.