One cannot judge thoroughly enlightened people by their actions. One cannot say whether their actions are sinful or sinless. Buddhist saints and sages appear to be no different from ordinary people, but they are. This creates problems. Since the time of the Buddha, people have judged saints and sages and have found faults and shortcomings in their actions; but they rely on their distorted, narrow-minded world view. Sages and great practitioners are open-minded in the truest sense of the word, and they have no concern for the petty conventions ordinary people prize so dearly.
Yung-chia reminds the unenlightened not to judge great practitioners, especially their own masters, by their narrow-minded standards. You study under a master in order to benefit from the Three Jewels. If you have doubts about the teacher, you will have no confidence, and your practice will suffer. That is your problem. You may even raise doubts in other students' minds. That would still be your problem, and it would be pitiable.
A Chinese saying encourages us to see others with the eyes of human beings, not with the eyes of dogs. In China, dogs do not enjoy the same treatment and respect that they receive in the United States. The Chinese belief is that dogs will not bark at well dressed people, but will growl and snarl at people dressed in rags. Believing and following such stereotypes is sure to lead to mistakes, doubts and harmful behavior. Students should not doubt great practitioners, and most especially not their own masters. If you have no confidence in your master, what can you possibly learn from him or her?