It is not suggested that you go around canceling interviews that you set up for yourself or that your recruiter sets up for you, but there are occasions where it may be appropriate to cancel your interview. Often times, you are not familiar with a company until you begin to research them prior to your initial interview. I personally have all of my job seeker candidates thoroughly research a company prior to any interview and come up with at least "5 reasons why they want to work for the company, 5 reasons why the company should want to hire them and 5 questions regarding the position." If a job seeker cannot think of 5 strong reasons why they might want to work for this employer, then the position might not be worth going in for an interview.  I respect and appreciate the job seeker when they get in communication with me early to let me know the position might not be the right fit for them.