Rubber Duck
Yoda
Yoda's reliability presents a more complex profile. His counsel, whilst often profound, arrives encoded in deliberately obscure syntax that requires significant interpretation. His tendency toward riddles and indirect teaching methods has frustrated students throughout the millennia.
Furthermore, Yoda has demonstrated a willingness to withhold critical information—notably regarding Luke Skywalker's parentage—when he deems such knowledge potentially harmful. This paternalistic approach, whilst well-intentioned, introduces unpredictability into the advisory relationship.