Hollywood put out several productions that proclaimed the USSR was a paradise. [1][2]
US and European industrialists had gone over to the USSR pre-WW2 and helped them build out their industrial base. The Soviets had entirely failed at industrializing on their own. From those experiences, and people writing about them, it was fairly well known what general condition the USSR was actually in economically. Firm, reliable metrics however were largely unavailable throughout the Soviet era.
The fooling of the West, regarding the Soviet's mighty materialism output, mostly fell apart by the 1960s (the facade lasted for ~30 years or so, and mostly only for people that were sympathetic to that ideology).
[1] https://en.wikipedia.org/wiki/The_North_Star_(1943_film)
Do you mean blatantly obvious at the time and from outside? Could you please elaborate? I thought the USSR put up a good front, and fooled much of the West with regard to economic development (not freedom).