Why can't we smell our own bad breath. Is there any way we can do that?
closed as primarily opinion-based by Bez, WYSIWYG, Chris♦, fileunderwater, Amory Oct 16 '14 at 14:14
Many good questions generate some degree of opinion based on expert experience, but answers to this question will tend to be almost entirely based on opinions, rather than facts, references, or specific expertise. If this question can be reworded to fit the rules in the help center, please edit the question.
What you might be experiencing is olfactory fatigue, the temporary, normal inability to distinguish a particular odor after a prolonged exposure to it.
It's a form of neural adaptation, a change over time in the responsiveness of the sensory system to a constant stimulus. This adaptative mechanism might prevent the overloading of the nervous system.
However, some people (maybe most of them?) are able to smell their own breath. At least, I know I do. I can't point you to any statistics, but it might be an interesting research project, figuring out how many people can smell their own breath.