The Demon of Insincerity is a demon who tricked Milo, Tock and the Humbug--and when unseen always tells lies.
He is small and furry with worried eyes and a frown. His eyes are not green and he has a narrow mouth, thin neck, narrow, long arms, small feet and a button nose. Despite his insignificant body, he has a great voice. He is actually a really adorable creature for a demon.
He is very easily scared and saddened and when unseen everything he says is a lie. He pretends he has a long nose, green eyes, curly hair, a wide mouth, a thick neck, broad shoulders, a round body, short arms, big feet and is bow-legged. He does this to trick people. He uses his voice to trap Milo, Tock, and the Humbug in a pit where they can only hear him. That is, until Milo uses the telescope he got from Alec Bings to see the demon as he really is.