The best that I have seen is one of the mutations of the red rump parrot. They started off with an undesirable,naturally coloured,emerald green bird with shades of rich blue on it's wings and a fiery red rump ( all apparently too gaudy) and they produced a magnificent bird in near death shades of beige, brown and other earthy tones. Many years of breeding were wasted on producing these specimens, as the price reflected.
I don't know what this mutation was called and furthermore I don't care! I hope they all die out!
If breeders really want to experiment with genetics why not use sparrows and develop multicoloured ones that would rival any parrot, or develop a spice finch with feather extensions and colours to resemble miniature birds of paradise, not take the magnificent birds that we have and dip them in bleach. Having said all that some of the lutinos and other mutations are beautiful in human eyes, but have a plan other than "because you can."