Mix all ingredients (except for bacon) in a 4-6 quart slow cooker.
Give the mixture a good stir.
Cover and cook on low for 3-5 hours.
Stir the beans gently a couple of times during cooking.
Right before serving, stir in cooked bacon (if using).
Notes
The barbecue sauce is really adding the most flavor to these beans. So use one that you know you love. If you want a smokier tasting bean, then try using a hickory barbecue sauce.