Smoke-filled Room Meaning

Example : Used other than as an idiom: see smoke,‎ filled,‎ room.2009, Robert McCrum, "No Tóibín, no Trevor? Yes, it's time for more Booker controversy", The Guardian:  In its first decade, prize business was settled in the smoke-filled rooms of London clubs, where it remained resolutely insular.2013, Ted Cruz, "Ted Cruz Punches Back", National Review:  If the forums in which we make this case consist of the smoke-filled rooms of Washington, the votes aren't there.