I didn't watch Yu-Gi-Oh! 5Ds this morning, but I did watch the original Yu-Gi-Oh! I'm actually surprised that they didn't censor Yami Marik as much as I thought they had. He looked completely crazy, but they just left him alone. I know that they censored some of his antics, like his licking of the Millenium Rod, but for the most part, they let him remain creepy throughout the arc. That's weird.
Unless he is doing something like licking his rod or about to stab someone with the rod, his insaneness is kept the same. He is a lunatic so they do need to show him as one. They just really edit his stabbing stuff, like stabbing his father, about to stab his servant, stuff like that. Yami Marik is like the most insane Yu-gi-oh villain ever. Which is why he is so cool.