I have no idea how fashionable it was, if ever, to admire the Soviet Union, I just picked the example at random.

In the years immediately following the revolution it is probably fair to say that the cultural elite of the American left (Greenwich Village, Bohemia, the Beat movement) admired the Soviet Union. John Reed's thoughts are probably representative since these people were hearing about the USSR from him. The CPUSA was sort of hip for a while, as well, through WWII. I'm not sure "classy" is the right word but these groups did hold a certain kind of social status that would have attracted young people. By the 1960s though, the same types of people would have admired Third World leftist movements rather than the Soviet Union.