Oddly enough, my mother (a high school theatre design teacher) has adopted the same approach. First she started off with tints and slight modifications, and currently she's up to a maroon color that slowly fades back to brown. She has expressed a desire for green or blue hair, but doesn't yet think she can get away with it. Though when discussing the matter with her school's principal, the principal said something to the effect of, "Well, fewer of the students would do it then." :P