I grew up with the Berenstain Bears and always knew how to spell them. But I totally recognize there are other things where the touchstone I used to try to remember something was indicated by others to be faulty and I couldn't select decidability between my memory echo and their evidence. Fruit of the Loom is one I have trouble with; I also keep trying to put "bases" into "All your base are belong to us".

I suspect that there are slippabilities that are so common as to be shared experiences and this boosts their signal when discovered at the Mandela level. There will of course also be corporate and government denials of the past, which is normal, but those can usually be disproven quickly like emperor's clothes. It's those borderline cases where many independent memories appear to challenge something (and this challenge also appears grassroots and not manipulative) that leave the question open.