A good color means natural. Look carefully at a fistful of hair in the mirror. See how each strand has a different tone? Perhaps even different colors on one strand? These are the natural striations that Mother Nature gives each head of hair to work with natural lighting. A good "color job" must duplicate these natural highlights to be effective.
Hard as it is to believe there was once a time when those who colored their hair were looked down on by "respectable" women. Some would sneer, "She gets her color out of bottle, you know." Making it sound like that was a bad thing.