But how can one know whether one has permission? In reality I think one is going to have permission from some, non permission from others and total indifference from many.
I don't feel that non-Western cultures who adopt fashions from the West, or food, or dance, music, etc have appropriated anything. They've just enjoyed it and cultures have mixed. I'm for maximum mixing of the best parts of all cultures.
Scottish dance is an example of something that is enjoyed all over the world. Many, many countries have branches of Scottish dancing clubs affiliated to the Royal Scottish Country Dance Society. I was involved with that society for nearly three decades and I never heard anyone complaining about Scottish dancing being appropriated in other cultures, only pleasure that people all over the world got as much fun out of it, and its music, as we did.
I think accusations of cultural appropriation are just sourness.