Being a good teacher of Jiu Jitsu requires having a sense of honor. You need to be in it for the love of martial arts, rather than for the money that you bring in for your classes and lessons. Also, you should be concerned about showing only the good aspects of Jiu Jitsu and the right way in which to practice.
It is not possible to control how everyone teaches, but if you have a sense of dignity and your own teaching is effective, people will recognize what is ineffective in what other teachers do. Show your students how passionate you are and you are sure to instill it in how they learn and practice.