I came across these qualities of a good teacher by Ms. Marie F. Hassett. Every ESL teacher must be good and therefore must possess the following qualities:
Good teachers
have a sense of purpose,
have expectations of success for all students, tolerant to ambiguity,
demonstrate a willingness to adapt and change to meet student needs,
are comfortable with not knowing,
reflect on their work,
learn from a variety of models,
enjoy their work and their students.