When Dave Chappelle dressed up as a white reporter on his infamous show, it just looked weird. And he used this overly proper "white accent" that seems to be the norm for Black people impersonating white people.
In the film White Chicks, Marlon and Shawn Wayans dressed as white girls and it was just creepy looking.
Just a few minutes ago I saw a video of comedian Druski playing a white redneck at a NASCAR race. I'm literally a NASCAR loving redneck and he's a more believable redneck than I am. Hahaha. Hilarious. The makeup on him is mindblowing. He even sported a sunburn. I officially bestow upon you my redneck seal of approval. Somebody give this "white man" a movie role.