By the Brezhnev era, the corupted Nomenklatura that had been first peering over the fence under Malenkov had finally come to age with the corrupted parts of the CPSU using illegal and discreetly placed drably painted doors to secretly find converted basements full of the forbidden pleasures of capitalism, such as drugs, prostitutes, posh food, Rolex watches, Havana cigars and so on....
The doors them selves
They were hidden away in less visited store rooms, closets, basements, toilets, tool sheds and alike. The doors looked like a firther set of security locked toilets, storage locker doors, closet doors, maintenance hatches, tool shed doors and\or fire exits. Only a very few knew the truth about these doors!