An unhappy fact about human psychology is probably at work here, which makes it hard to abolish lies once they have escaped into the world: We seem to be predisposed to remember statements as true even after they have been disconfirmed. For instance, if a rumor spreads that a famous politician once fainted during a campaign speech, and the story is later revealed to be false, some significant percentage of people will recall it as true--even if they were first exposed to it in the very context of its debunking. In psychology, this is known as the "illusory truth effect." Familiarity breeds credence.
