There is an interesting story of a group of people who decided to go and study under a great Tibetan teacher. They had already studied somewhat with other teachers, but had decide (sic) to concentrate on trying to learn from this particular person. They were all very anxious to become his students and so sought an audience with him, but this great teacher would not accept any of them. “Under one condition only will I accept you,” he said. “If you are willing to renounce your previous teachers.” They all pleaded with him, telling him how much they were devoted to him, how great his reputation was, and how much they would like to study with him. But he would not accept any of them unless they would meet his condition. Finally all except one person in the party decided to renounce their previous teachers, from whom they had in fact learned a great deal. The guru seemed to be quite happy when they did so and told them all to come back the next day. 

But when they returned he said to them, “I understand your hypocrisy. The next time you get another teacher you will renounce me. So get out.” And he chased them all out except for the one person who valued what he had learned previously.

… If you are going to make friends with a spiritual master, you must make friends simply, openly, so that the communication takes place between equals, rather than trying to win the master over to you.

(Cutting Through Spiritual Materialism by Chogyam Trumgpa, pub. Robinson and Watkins Books Ltd. 1973)