Appreciation vs. Appropriation: Where is the line?

A college acquaintance with whom I'm Facebook friends posted this article about Katy Perry's new music video.

I responded with the following:

[Friend's name], thanks for posting this. I've been thinking about it for a while now, and I'm reaching out because I'd like your help. I read the article, and I definitely feel funny about aspects about how Katy Perry was styled and how she acted [...] There's clearly some "line" in my mind that she crossed. But -- and I recognize that I'm asking this from a place of extreme privilege, and I'm willing to be told that what I'm asking is ignorant if you can help me see why -- before that "line" of ok vs. not ok, is there room for seeing something and wanting to try it too? I also was struck by how the article called it "the difference between appreciation and appropriation." Where do you think is the difference?

My friend and others responded with great, helpful, insightful answers. Now I'm reaching out for your help -- whoever you are, reading this post.

What do you think is the line between appreciation and appropriation, between ok and not ok? Is there room, as I asked above, to see a habit or a practice associated with a certain sub-culture and to use it in a loving and respectful way? Does that question itself smack of privilege?