Then you may have a UV texture or backfaces
Elaborate, what do you mean by "I may have a UV texture" Its not a backface problem the lighting isnt backwards, only super-contrasty and looks like stuff. Ive tried the cube trick several times consecutively and it didnt work either time. I select the cube first and then the mesh to keep the parenting and name, is that a problem?
Edit: Nevermind, thats exactly what it was. You should specify that you have to select the part of your model FIRST and THEN select the cube, Im sure that Im not the only one who was confused with that.