I would think so, and it gets harder for them due to globalisation and countries working together economically (well apart from Russia maybe) - because back in 1949, China, Korea and Japan were basically impenetrable black boxes for most people, where you'd take the CIA's word for it because who knew what was possible or likely in those cultures?

I wonder why people believe them now, to be honest.

I'd say it depends. Which "CIA fabrications of today" are you referring to?

Many people likely have something that springs to mind, based on their own existing biases, but that differs between people. When naming a particular "fabrication" you'll probably encounter much more resistance. (Russiagate? HIV/AIDS? The moon landing?)

Remember all the accusations of Julian Assange being a rapist?