Eli5 (and a German) the problem with black facing.

So I rewatched Pulp Fiction last night and thought it would be so nice to dress up on a Party as Jules, bringing a Big Kahuna Cup to drink from and quoting Ezekiel 25:17 and all. To me this would be an act of showing how cool I find him. In general I think dressing up as someone else could be considered a compliment to them, as it shows you'd like to be them, if only for a night.

So I am probably missing something here! (I know it is a touchy topic and it's not my intention to step on anyones toes.)

Edit: Added missing verb "showing"

Edit 2: Of cause I knew it is problematic! (Although I underestimated how much) I never had the intention to actually do more then fantasize about it (there isn't even a real party coming up, it was just a thought), however I was interested in the American and the European (German) perspective. Seeing how lively this discussion is, seeing how very differnt the arguments and perspectives are, and reading all the interesting background information (I had never heared of "Minstrels"), I am very happy I asked!