Popular images are hard to erase. We could tell all about Che in a TV documentary and there would be millions of Americans who would reject it and millions more who would say: "Eh?" There are multi-millions across the world.who have rejected the truth about the Holocaust during WWII, about the Armenian massacre during WWI, about any number of historical events. They either reject them totally ("that didn't happen") or they add or subtract details to enhance their opinions and minimize others'.
The only thing we can do is for each of us to preserve truth to the best of our abilities. That means making sure that what we believe conforms to truth. It's never perfect, but at least we can move in the direction of perfection, and not away from it.