Males tend to have yellower heads that remain that way as they get older. Some females will have yellower heads when young but the white comes up as they get older.
It is a matter of the color thickening. Water quality and food quality also helps.
Look to the body first, then to the quality of the skin, then to the quality of the color, then to the attractiveness of the pattern...
And remember, the best you can hope for is that you get what you pay for.
