You have to watch out for the "water dowser" effect. If you're in front of a group of people who have no ability to check your answers, it's very easy to convince them that you're always right. If a trusted person with good social skills came in and said, "don't work with him he's not earnest," how would the room ever find out whether he was or not? They'd be unlikely to trust him enough to end up in a situation where they'd be able to see for themselves.