Badminton, like tennis, is a racket sport that is played by either two players or two teams of two players each. The object is for you or your team to get to 21 points first. You score a point whenever you successfully serve the shuttlecock and your opposing team commits a fault, which means that the team fails to appropriately return the shuttlecock.
Assuming one cares for their teeth by brushing regularly, saliva may smell bad because there are millions of bacteria present in the mouth. Bad smelling saliva or breath can be indicative of a tooth abscess, or a systemic illness such as diabetes.
If you do not make enough saliva, your mouth can become quite dry. This condition is called dry mouth (xerostomia). Dry mouth causes the gums, tongue, and other tissues in the mouth to become swollen and uncomfortable. Germs thrive in this type of setting. A germy, dry mouth leads to bad breath.