Culture cannot be copyrighted or be subject to intellectual property rights. I think the offence taken comes from people who lose the meaning behind something, though, which is still vague to me.
For example, an American Indian headdress is a symbol of the greatest respect in a tribe; it is something earned. However, wearing them at festivals and so on, I can see how it can be disrespectful to real American Indians.
I am uncertain on which way really. I can understand the disrespect, but I can see that a physical item of clothing is not necessarily important. However - there are cases where clothing must be adhered to - for example, I can't go around wearing a police uniform, or wearing a crown that looks like the Queen's. So this is quite a complex issue.
Behaviour cannot be copyrighted. Mannerisms, gestures, etc., belong to individuals, not a culture or race. Which is why if I say 'My name is Michael Caine' in the accent, that's an impression of an individual. Things like gestures, mannerisms, and accents, can only be tied to an individual - they are not part of a culture. Yes there are stereotypes, but those are only stereotypes. They do not define a culture.
Labels are human creations only. They do not define us. They are only to help us categorise, summarise and predict. Trying to label everything is futile.