Old Man Pann is impressed that Adrian's dimensional sense seem to be more perceptive than others. Even other Arch Demons will have difficulty in sensing the movement of Cosmic Cetacea in different dimensions. The movement of Bessie, the Cosmic Cetacea, is not just vanishing and appearing in different places.
One would think that the Cosmic Cetacea perceive space like the Daemos but that is not true. The bodies of the Cosmic Cetacea would dive into other dimensions that are in a different layer than the real one. This gives the illusion that they vanish to those that only use their sight. For a perceptive Daemos, they can feel that something is moving within the dimensions.