How do I filter out bad students from tutoring?
Run an introductory test

You're looking for students that can manage their time and responsibilities. The only way to test that is by trial. Prepare a short questionnaire that would give you an impression of what the student knows. Send it to the student several days before your first meeting and ask to complete it before the meeting. Depending on how strict you want to be, do or do not remind the student about this test. If the student completes the test before the meeting, he's more likely to turn out a responsible adult. Apart from that, the test provides a starting point for your first meeting.

Note: in my culture, first meetings with tutors are usually unpaid and considered a trial period. It's easy to drop a student after a trial meeting if he didn't do the test and didn't seem hardworking during the meeting. If you already established a payment routine, it's harder to drop a student.


  It's a waste of my time and their money to have me repeat definitions to them an hour a week, week after week.


For a lateral approach to the problem, grad students who recently started tutoring sometimes only plan to tutor brilliant students, like themselves. Because of that, new tutors think that the job will be pleasant, thought-provoking and fascinating, so they set a lower hourly wage. However, an hour spent tutoring should be properly recompensed, even if it was dull to the tutor. I'll leave for you to judge if my experience applies to you, but don't hesitate to raise your hourly rate so that you don't feel like you're wasting your time.