Teachers are formally wiser then us. They use their wisdom to guide us.
Have you have started to disagree with them (silently or not), and your intuition tells you that they lack the wisdom you once believed they had, and even worse: you get the sensation that you yourself have a better grasping of the fundamentals? For example they have a seemingly correct, but yet shallow way of applying or communicating the teaching.
Some things are obvious signs of lack of wisdom such as breaking the percepts or similar things, but I think more of the overall feeling you get about the persons understanding, and the sensation of the persons grasp of the more subtle details.
You might leave the teacher because of your intuition, but wouldn't it signify a lack of respect to follow your own intuition, instead of trusting the person said to be wiser then you? No matter how strong your intuition is, you may still be affected by delusion while the teacher is not. How can you ever know?

