Why can’t a person smell his/her own bad breath? At least, difficult to?

bad breath
BBHunter asked:

People often blow into their hands or try to breath upward to their nostrils and still can’t tell. Why is this?
Sorry, I chose the category “other” accidentally. I quickly misread “other” as “oral”.
For those that are saying, “you’re used to it”. If 2 people had the same bad breath, you’re saying they can’t smell each other’s bad breath? i’ve seen instances where 2 people with bad breath (same breath when I smelled it) point at each other for having bad breath…and they were both right.