The students must be the focus; they are not there to see "you." They are there to learn and who the instructor is not of immediate importance, especially if they are new students. If the student has been on campus for more than one or two semesters they will hear about you from other students (or instructors) and they may make a judgement before they even meet you because an instructor's reputation precedes him/her. But, no matter what the instructor's personality, the goal is to give the students the education they have paid for and expect. After all, without students instructors no longer have a job or a paycheck.