Good one guys.
Here's another one I found today. It's a college student in UCLA who dressed up in a Poncho, fake mustache, and a sombrero. A real Mexican stereotype. He went on campus and asked the non Mexican students if his Halloween costume was offensive. Most said "yes" that they were offended. The same person went and interviewed native Mexican's. None of them in the video were offended. They seemed to have a sense of humor and confidence in their culture.  Also, I imagine the context of the person wearing the costume is paramount. I would only say that wearing a costume of another culture would possibly be offensive if the persona was demoralizing or demeaning the culture itself.

Here's the video.
https://www.youtube.com/watch?v=IT2UH74ksJ4

From a sociological perspective, it is interesting to see this unfold.