With maniac players, it's easy to get into the mindset, "He's obviously got nothing, since he does this every hand. I can call lighter than normal and still be ahead of his range." While this is typically true, you WOULD be ahead of his range, that wide open of a range can hit more, and bust you. And that is the mentallity that they WANT you to take, because when they actually have a good hand, they will be called by weaker hands, and make bank.