There are several websites where you can find out if you are on Santa's bad list, including Santa's Net, emailSanta.com, and The North Pole Times. The best indicator over whether or not you have made Santa's bad list is the contents of your stocking on Christmas day.
Santa expresses his disapproval of people on his bad list by placing coal in their stockings when he is out delivering gifts. People can avoid Santa's bad list by performing good deeds, taking care of their chores, and being respectful to their parents. When in doubt, people sometimes attempt to bribe Santa at the last moment by leaving him cookies on Christmas Eve.