I'm not sure what stronger sources you could expect than from embassies. Travel wasnt as common or as free as it is today. Russian and Western societies were c

I'm not sure what stronger sources you could expect than from embassies. Travel wasnt as common or as free as it is today. Russian and Western societies were completely cut off. The only real sources you would have is word of mouth. The word of mouth was likely to be a reporter or an embassy worker. Otherwise the odd tourist, but I'm not sure how a tourist was supposed to gauge the impact of Grapes of Wrath in another country and/or why a tourist's word should be held above those of reporters/embassy workers. The reality is that everything we know about life behind the Iron Curtain since it came down indicates that there is no reason this couldn't happen. Cars were extremely rare and expensive in the USSR. Cars were significantly cheaper and plentiful in the United States. The only point of contention is whether people living in the USSR watching a movie about the United States would be fascinated by the fact that even the poor in the United States had cars, something even middle class to rich people in the USSR could not obtain easily. That seems a fairly narrow point anyways, whether true or not.