Bad breath has never been a good thing, it is caused by dirtiness, our people here in Nigeria call it mouth odor.
Bad breath is caused by odor-producing bacteria that grow in the mouth. When you don't brush and floss regularly, bacteria accumulate on the bits of food left in your mouth and between your teeth. The sulfur compounds released by these bacteria make your breath smell. It is shallow of a person to not brush his teeth, it is just so bad, and for kids they ought to be taught to brush everyday, if they aren't capable, their parents need to brush the so they don't develop bad breath.
However, it is not only caused by not brushing but by smoking and drinking. If you live close to such people, you can testify of these. drunkards smell alot, not only their mouth, but their body too.
Nevertheless, foods like garlic and ginger can also cause the mouth to smell.
Bad breath can also be caused by surgical wounds after oral surgery, such as tooth removal, or as a result of tooth decay, gum disease or mouth sores. Diseases, such as some cancers, and conditions such as metabolic disorders, can also cause breath odor as a result of chemicals they produce.
I really haven't seen a possible cure, but to prevent it you need to take precautions, brush regularly, at least twice a day, avoid smoking and drinking, when you take in food like garlic, onions and ginger make sure to brush your teeth with a good paste, a paste that possibly contains also vera.