At least in the Kantian sense, the guy was not really bad in that he didn't really intend to do much harm. His writing is very tied to bringing Christianity to Caribbean tribes, some of which were still actively practising cannibalism. He "scammed" them by trading glass beads for gold, but that still feels somewhat minor. I wonder if people don't sometime confuse him with Cortés (who was a true piece of work) and the later stage of Spanish colonisation which all happens several years after the death of Columbus.