Many individuals with bad breath may be unaware they have it, or their signs and symptoms may only be temporary. The odor often depends upon the source or underlying cause of the bad breath.

Sour or Metallic Taste.
Volatile Sulphur Compounds (VSCs) not only smell but also taste foul. If you have adequate saliva, then the first thing that happens is the volatile compounds will dissolve into the saliva allowing you to taste them. It is only after your saliva becomes super saturated with compounds or you exhibit dry mouth where you do not have enough saliva, that the compounds will evaporate in to mouth air and then be pushed out with your breath or on speaking.

Halitophobics Have Nasal Mucous
Generally halitophobics have throat smells, that travel to the nose where they are able to be smelt. But these gases are blocked off by the throat and do not travel to the general public. So you get friends or doctors telling the person they do not have bad breath when in fact the sufferer can smell the breath 24/7.

Metallic Taste May Mean Dry Mouth
But it is not all so simple. If you have a metallic taste then this may be an indicator of dry mouth. Metallic taste can also occur if you chew too much chewing gum with artificial sweeteners, or if you use mouthwash with chlorhexidine or mouthwash with chlorine dioxide in it. If you place acid in your mouth, such as with coffee or commercial mouthwash then this also can cause a metallic taste. Finally acid will happen after every meal, regardless of the food being healthy or not. So the secret is not to snack on foods but eat breakfast, lunch and dinner. If you are still hungry then have morning tea and afternoon tea. But do not snack on foods in between these meals.

Tongue Coating.
Just as you get a coating on your teeth called plaque, everyone gets some coating also on their tongue. This coating is generally a mixture of sulphur compounds mixed with mucous and sometimes food particles or coffee or tea and probably bacteria. If this coating is not cleaned away every 24 hours then it will mature and allow bad breath bacteria to live and grow within.