We don't need any more mediocre ones. The best schools in the U.S. are in Hollywood. But even more important are the instructors. The school is only as good as the teachers. Often they change from week to week.
Many schools use professionals who work in the field.
Of course teaching doesn't pay as well as working on a film or TV show, so the best time to get an education is when it is slow at the studios. Make sure you see the resume and if you can the portfolio of the instructor who will be teaching you, when deciding on a school. You can get a pretty good idea on our message board of who's hot and who's not. See our links page for a list of schools. Technique of the Professional Make-up Artist by Vincent Kehoe.