First thing I thought of when I read the title.
If the Mario RPGs have taught me anything, it's that Luigi is a jerk. He lies to people constantly, is jealous, entitled and whiny, talks about how he could accomplish stuff if he wanted to, and bails on people in need constantly. In fact, the only reason Luigi had his own sub-series is because he was conned into accepting a fake prize for a contest he didn't enter. What a dumbass. It's a good thing the Mushroom Kingdom doesn't have internet, because he's probably be concerned about ethics in video games journalism. Gooigi is clearly the less slimy Mr Green.