Bad breath is embarrassing and can be inhibiting to your personality. It will also turn people away from you. A good smelling breath leaves a lasting impression.
It is caused primarily by bacteria in the mouth. In the morning most people have nasty breath which goes away by brushing. But if there is build up of bacteria, bad smell might come at other times also.
The best way to find out out if you have bad smell is to ask people close to you and figure out.