What really bamboozled me was Kirk's "friend" Tyree in "A Private Little War" who seemed to be from a culture barely out of the Bronze Age, yet had full knowledge of the Federation AND Klingons and was serving as a proxy world for their "Cold War". Then there was the odd dual culture in "Omega Glory" that Captain Tracey was exploiting, and the Enterprise crew visited, without hiding their uniforms, weapons or any other aspects of advanced civilizations, the poor misguided Vaul-followers in "The Apple", and the list goes on. Scores of pre-warp cultures had plenty of a-priori knowledge of spacefaring empires. Then there were the other places that seemed to have no real problem with it, like in "A Piece of the Action", "Return of the Archons", "Bread and Circuses", etc. And those were just the places we were actually shown. The amount of "cultural contamination" throughout the galaxy seems endless.