is the "lick your palm and sniff it" method: the bacteria that cause bad breath are more concentrated in saliva than breath. Erm, so I'm told

There is already an iPhone app that does this.

You just breath into the microphone.

"..the test kit will turn blue .."

Just don't get it confused with another self test product.

@Phil Endecott :- I spent some time thinking about that - damn you!

...for a synthetic replacement for the human mouth.

It's stinky, the teeth rot easily and often require painful surgery and most just plain don't look nice

Also a decent set of cameras for eyes would be nice. Zoom lenses anyone?

But I'm getting off topic.

This reply prompted me to propose marriage:

"You smoke, you drink beer and coffee, of course your breathe stinks. Lucky for you so do I"

The anon cow who asked for cameras for eyes, google Rob Spence.