Identifying instances of celebrity cultural appropriation has become increasingly published mainstream fodder. The good intentions of politically recognizing and reconciling power relations evaporated when cultural appropriation became a profitable context to write about the arbitrary actions of celebrities - when it became fashion.
Like globalization, cultural appropriation is a neutral process that has both good and bad implications. It has always and will always be happening. The argument that cultural appropriation is an inherent evil inadequately/incorrectly defines culture as a product owned by a group determined by biological descent.
Marxist and essentialist theories define culture for the zealous opponents of cultural appropriation. Marxism suggests that culture is a good that is produced and owned, and essentialism adds that cultures self-reproduce by creating immutable stereotypes of themselves. Cultural appropriation is always bad if you believe culture should be owned by its "rightful" creators, who are "authenticated" by stereotypes.
Post-modern theories offer a more accurate account of culture as a set of practices that characterize a distinct group of people. There is no division between culture and knowledge; culture is language, music, dance, dress, food, storytelling, political traditions, sports, and relationships with animals and environments.
Calling cultural appropriations injustices also misrepresents consensus on what injustice means. The dominant narrative of injustice is an understanding that an unacceptable rights infraction has occurred and requires remedy. If you can't directly replace the words "cultural appropriation" with "racism" in your pop cultural critique, you're probably missing the point.
Speaking of all cultural appropriation as injustice proverbially throws the baby out with the bathwater. The effort to curb injustice incidentally commits injustice through heavy-handed cultural policing.
Cultural policing is a censorship phenomenon with roots across the political spectrum. Conservatives eschew sex, violence, and non-traditional values in TV, film, and video games. Meanwhile, progressive factions have taken to policing 'insensitive' cultural elements. Regardless of motivational divergence, all practices of cultural policing present relative moral narratives as justification for challenges to free expression.
An instance of cultural policing can be of net benefit when it's motivated by the correction of injustice. I do not write "the pursuit of justice" because the tense of cultural policing is the point where the practice pivots between corrective and intrusive. Using a flawed method to correct a flawed world is reasonable, but using a flawed method to create an ideal world is illogical. Cultural policing is either corrective (justified) or moralizing (intrusive).
The corrective capacity of cultural policing is assumed in the project of political correctness. Political correctness is a commitment to correct injustices that language conventions (re)create. Solidarity across immeasurable difference and individual accountability for words spoken into reality are the desired outcomes of political correctness. The cultural policing of political incorrectness is justified because it corrects unequal power relations actively and passively entrenched in language.
Moralizing instances of cultural policing from progressives are motivated by the movement toward empathetic correctness, a doctrine that asserts that individuals should take responsibility for the emotional reactions to their free expression. Empathetic correctness is an approach to build a specific and contested vision of justice at the cost of civil liberty. Empathetic correctness values a non-offensive character to culture over the critical consumption of freely produced culture.
There's just one glaring problem with empathetic correctness. Hurt feelings are not injustices.
The power relations that need to be critiqued between privileged and underprivileged cultural producers is legitimate in a context of plagiarism. Plagiarism sets cultural critique in the paradigm of intellectual property rights. Imitation within reason is acceptable, but there are economic rights protecting intellectual property. Where rights are infringed, there is injustice.
Definitively, it is within your rights right to both culturally appropriate and police, but I implore you to consider why exactly you're doing so. The world would be a better place if people stopped to ask themselves "is my costume fetishizing or trivializing anyone?" or "is my public confrontation/keyboard call-out based on a subjective moralizing argument?"
Reflection is better than judgement.