This seems like a very opinionated question. What do you look for in an instructor? Really it sounds like it is a subjective question. It can certainly vary from person to person, but when you look at those instructors who have students that continued to train, continued to teach, and continued to pass on the art, one thing sticks out when it comes to what they think you should look for in an instructor.
Whether it be Gichin Funakoshi or Bruce Lee, the common point in their definition of what an instructor should be, is an instructor that demonstrates the technique and leads by example.
This may seem superficial and we can say that this simply means an instructor that is in shape and has good technique, but the sentiment rides much deeper than this.
You see, my friends, an instructor that demonstrates is an instructor that is mentally secure in their technique and is confident. There will be others that, sure, have better technique than the instructor somewhere on the planet, but this instructor is able to stand in front of a large group of students and perform their technique without worrying about the criticism. This instructor is not pretending to be something that they are not. They are comfortable in their own skin. This personal integrity will allow them to guide others well and create future generations of martial artists. In any instance, vulnerability is important to developing any relationship, even one between a student and instructor. Without vulnerability in friendships, we find that we have fake friends or a romantic relationship that is about to go sour. What is that to say about the truth and honesty that we have with our students?
There are plenty of people that I have seen on social media that go and edit their side kicks out of their form videos. These instructors are hiding things from the public. There might be reasons for editing these things, such as having a condition that does not allow for techniques to be as asthetic as prescribed by the standard. These folks could have been injured. At the end of the day these folks have an insecurity. They worry what others think of them.
Do not confuse insecurity with self consciousness. Insecurity means “I care what you think about me”. Self consciousness means “I care what I think about myself”. At the end of the day there will be a certain degree of self criticism with the martial arts and that is normal. When we demonstrate our techniques we show to our students that we are human, and that while we may not always be comfortable with our technique, we are comfortable with our ability to provide an example to those that know less than we do.
Do you demonstrate for your students? Many times, they do not worry about seeing perfect execution, but being able to see the beautiful and artistic expression of our imperfect executions.