The Rage Wireless Wii guitar from Performance Design Products has been recalled due to its tendency to burn human flesh if not handled correctly. Well, it burned one set of flesh, at least, and that was enough. According to the official recall, if the batteries are installed incorrectly, something with the circuit board will cause those batteries to leak. That can't possibly enhance your fake-music-playing experience. If you happen to have one of these, check the manufacturer's website for more recall information.
Do not buy (or keep) guitars that have the potential to hurt you worse than you have ever been burned. Buy a safe guitar instead. Y'know, like one of these.