Just as beauty is in the eye of the beholder, music is in the ear of the listener. That's why there'll never be agreement by everyone on anything as varied as music. Besides, the definition of "mediocre" is "of only ordinary or moderate quality; neither good nor bad; barely adequate" which implies the application of some standard of quality that is not subjective. Obviously any person's opinion about music is almost totally subjective based on whatever standards the person chooses to apply. This debate will always be a debate, never a concluded argument.