The word misfeasance is legal terminology. It refers to someone performing incorrectly even though it is legal. (This is broader than lying when you don't know it's a lie.)
(Misfeasance is contrasted with malfeasance, which is known wrongdoing by a public official.)
If the speaker spoke the truth literally, but intended for the listener to misconstrue the statement, then he spoke a prevarication. (If someone asks about your education, and you say, "I went to Harvard," then you are prevaricating if you merely visited the campus and intended the hearer to think that you were educated there.)
Other possibilities:
telling an innocent lie
telling an unwitting lie
being a tale-bearer
I am reading Living Economics: Yeseterday, Today, and Tomorrow. Peter J. Boettke says
The Keynes of The General Theory was never right when it came to an an economy operates, let alone how to fix it when it teeters during crises.
While Boettke does not use a single word to describe this phenomenon, he might name a Keynesian as someone who "spreads incorrect lies as universal truth."
