but other people can?
The problem is, you can’t exhale through the mouth and inhale through the nose at the same time. 
If you want to smell what your breath is like, lick the back of your hand, and sniff it. This will give you a pretty good idea if you need to suck on a mint before your big date or not.
Doesn’t blowing inot your hand work…maybe not but everybody does it.
I don’t think either method is going to accurately reflect what your breath smells like to others. Your olfactory sense is so closely linked to your mouth that it would become desensitized to any resident odors. Like smelling a rose all day, pretty soon you can’t smell it anymore.
That makes sense.
I’ve heard this one, too. However, I was told to wait 15 seconds and then sniff.
It just tells me I have a smelly hand. I knew that already!
[Ralph Whigham]
My hand tastes funny. Heeaaa.
[/Ralph Whigham]
If you have a not-too-nice taste in your mouth then it’s quite likely that your breath pongs too.
I second the lick the back of your hand routine. I do it all the time. I don’t generally have bad breath, but i’m so paranoid about it I carry mints everywhere I go.
and brush your friggen tongue people! that’ll get rid of the bacteria for the majority of the day.
Some musicians certainly can breath out their mouth and inhale through their nose at the same time. It is called circular breathing.