Also, even falsified beliefs tend to be summarily replaced with new untested/not-intended-to-be-tested beliefs, e.g. "communism is good" with "correctly implemented communism is good", or "whites and blacks have equal average IQ" with "whites and blacks would have equal average IQ if they'd had the same cultural privileges/disadvantages".

I believe the common to term for that mistake is "no true Scotsman".