I definitely agree it would help if these people would visit and see for themselves. However, I think the propaganda point is more complicated than you portray. Many people are convinced US enemies are bad, not because primarily because they are tricked, but because it makes them feel better. They can feel better about their own circumstances in the west if they can say “at least I’m not in (insert enemy country).” This works in a peculiar way on the western left where it may work for them to think “It’s not our fault that we aren’t anywhere near socialism. It’s all China/Deng’s fault for betraying the revolution and bringing new life to capitalism. Now all the real socialism is on it’s back foot.” Those that aren’t total doomers from that thinking may add “maybe we could have an international revolution liberating us and the Chinese people from their chains.” This all ties in with the martyr fetish thing.

Another dynamic is contrarianism. Communists don’t want to believe the CIA/news/etc. The news says China’s an authoritarian socialist hellscape. The western Communist is confused. Are they good but not socialist? Are they still authoritarian but not socialist? Then they think of the other things mentioned in this thread or remember Lenin’s approach to the international situation around WWI and conclude China’s a rival imperialist. “China’s obviously doing capitalism so well that they are beating the old imperialists. They claim it’s socialist and uphold Mao in words because people know socialism is good.” This totally makes sense if you don’t engage in Chinese theory. It also makes sense when some of China’s most ardent English language supporters are clear revisionists. I’m speaking of the “Patriotic Socialists” and those like Micheal Hudson.