I've found that a small strip of silver duct tape blends in very nicely when placed over the Casio name on the back of the keyboard.
I was using it as a controller for a while and people were wondering what in the world that great-looking, great-sounding keyboard was. I tell them it's made in Italy and designed especially for people like me.
Now a friend of mine uses it for the piano and organ sounds in a four-piece band.
DonM