The arguement against wearing Native American headdress goes like this.
In Native American culture, he headdress and feathers have to be earned, rather like a soldier earns medals. Obviously, if I bought a Victoria Cross, George Cross, DSO and other medals and began wearing them inappropriately, people would take offence. The people who would be most offended would be veterans who had been awarded them for their bravery and courage. I would guess AOG would be outraged if some wimpy pop star thought it was cool to wear someone elses medals. Wearing a headdress that hasn't been earned is offensive to those who have earned it, like wearing someone elses medals is.
I am sure Miss Goulding meant no offence, so she wasn't being racist. When she was told why it was offensive, she made a donation to a Native American Charity.
These articles in the Mail are great when they are peppered with quotes from som back bench ignorant Tory bufoon.
This article may help
http://apihtawikosisan.com/hall-of-shame/an-open-letter-to-non-natives-in-headdresses/