I believe that in the wild you can judge the health by the color/richness of the head. However in captivity there has been so many mutations bred resulting in many shades of head colors, breast colors, back colors, and wing colors. Some of the leading gouldian breeders have produced the more orange head colors and these birds were on an equally sound diet. I am referring to Winnie McAlpin from Delmar Aviary. She refers to this color as Tangerine head. Here is a link to her tangerines
http://www.flickr.com/photos/11859828@N05/page6/
I have both head colors and like them both. I can assure you that the color of mine is not due to a bad diet, as they are all fed the same. It is simply the color of this line of gouldians. I like breeding for differnet colored head from blue headed dilutes to tangerine reds.. I have the cherry red color and what I call fire engine red colors also
Gouldian mutations can vary in shades just like a persons hair color. Depending on the genes that are crossed can have an effect on the offsprings hair color.
You must also take into account the breast color, back color and whether the bird is single factor of double factor. All of these this will contribute to the amout of color repressed due to the interactions of the genes at play.
If your bird has good feathering and has rich color in other areas then I wouldn't conclude that the coloring is from bad diet. Just the birds genetics. If it is due to the diet then with improvement and with the next ,olt you will see a difference. If it genetic this trait will be passed on. So if you do not like the color then you may not want to breed this bird. Though, I bet the color will grow on you, I have come to love them all
Male and Female deep red head colors: note, normal greenbacks
Fire Engine Red: note, single factor, purple breast, green back
Tangerine Red: note, white breast, normal green back

same bird
Here are a couple of red head females showing extreme differences in head colors:
White breast, yellow back and not the best quality
Another :
A beautiful, deep red headed hen:
You will also see the same shades in the yellow headed birds:
Deep Orange: note, purple breast, green back
Medium Orange: note. purple breast, yellow back
Note, lilac breast, yellow back
Light Orange: note, white breast, yellow back
