I figure it’s less telling what people want to hear and more saying one thing because MoM knows that they will do X to try to correct it. Like you said with the traitor was planting the seed of doubt which causes them all to turn on eachother.
Mn, good thought. Good thought. Probably depends on the person he's talking to. Like, telling them what they want to hear may work best on one person to get them going in the direction he wants, while saying something specific but obviously not something they'd want to hear would make another person do what he wanted. Master manipulators know what works best after all. Or both things. Like saying what they want to hear to get them to like him and trust him then saying what he knows will make them act the way he wants later on when he has their full trust and is certain it'll work.