1. Place slow cooker liner in the bottom of the slow cooker.
2. Trim fat off ribs, if necessary, and place ribs in the bottom of the slow cooker. You may need to cut the rack of ribs to allow to fit. In a medium bowl, mix barbecue sauce, sugar, Worcestershire and cayenne pepper, if desired. mix well. Set aside 3/4 cup of sauce and refrigerate. Pour the remaining sauce over the ribs and sprinkle generously with salt.
3. Cover and cook for 7-8 hours on low or on high for 3-4 hours.
4. Line a baking sheet with parchment paper.
5. When ribs are tender and the meat is falling off the bone, remove the ribs from the slow cooker and place on the baking sheet. Baste with the remaining sauce and broil until browned and crisping on the edges. (Can also grill instead of broil)
6. Cut and serve with any remaining sauce.