This is the key thing here - the "condition" of the tongue has more to do with bad breath than anything else. And, the further back on the tongue, the more significant it is. Yes, it is possible for an odor to originate at/from/in the teeth - for example, if food particles get lodged between teeth and rot; however, what contributes to bad breath more than anything is the tongue. Therefore, where bad breath is concerned, tongue scraping is more important than [even] brushing the teeth.