I have noticed on myself several times when sneezing for example, when as it happens, a strange not very nice taste erupts in the mouth for a second and then vanishes. It seems to come from the back.
Other times is when drinking water, and as it gets swallowed again a similar taste.
So it was interesting to find this article about bad breath and what causes it, I know I am paranoid about mine(but don't worry very much about garlic smells, for me they are natural) particularly in the mornings.
There are many causes of bad breath. Researchers have proved that the majority of bad breath (about 97%) is due to anaerobic bacteria (bacteria that do not need oxygen) that breed under the surface of your tongue, in the back of the throat and on your tonsils. These bacteria cause foul-smelling sulfur compounds called Hydrogen Sulfide (the same smell released by rotten eggs) and Methyl-Mercaptan (the dirty socks smell due to bacterial breakdown products in your feet when there is sweat and warmth in your socks and shoes).
Here are some of the signs and symptoms of bad breath:
You frequently have a bitter taste in your mouth
A white or yellow coating on your tongue
People seem to avoid direct contact with you and they step back from you when you are talking to them
People around you offer mints or chewing gum
A smelly odor when you open your mouth
Other causes of Halitosis
Certain foods
Foods such as garlic, onions and spicy foods etc. cause foul smelling breath after eating them. These foods are absorbed into the bloodstream, transferred into the lungs and become expelled in the air you breathe. Regular eating of such foods is likely to cause halitosis. People who diet are more likely to develop unpleasant breath from infrequent eating. You also get direct expulsion of these gases from your digestive tract.
Poor oral health care
Without proper and regular brushing, flossing and routine examinations by your dentist, food remains in the mouth causing bacteria to multiply and produce toxic waste which in turn causes breath odor. Food stuck on the teeth, gums, and tongue creates an environment where bacteria can feed and multiply. These bacteria release certain chemicals as a by-product which causes damage and decay of the gums and teeth. The chemicals that are released by the bacteria and the resulting decay in the mouth contribute to the bad breath.
Improper cleaning of dentures
Dentures that are not cleaned properly may be collecting bacteria and food particles which cause bad breath.
Periodontal disease
One of the primary symptoms of periodontal gum disease is foul, odorous breath, and an unpleasant taste in the mouth. This condition requires immediate care by an oral health professional.
Dry mouth (xerostomia)
This condition is often a large contributor to halitosis. It occurs when the flow of saliva decreases. Saliva is required to cleanse the mouth and remove particles that may cause odor. Xerostomia may be caused by certain medications, a salivary gland disorder, or by continuously breathing through the mouth instead of the nose.
Tobacco products
Not only do tobacco products such as cigarettes, cigars, smokeless tobacco and snuff stain the teeth and put the body at risk for a host of other diseases, they also contribute to bad breath. Tobacco products cause bad breath, stained teeth, reduces one's ability to taste foods and irritates the gum tissue. Tobacco users are more likely to suffer from periodontal disease and are at greater risk for developing oral cancer.
Medical condition
Bad breath may be an indication or symptom of any of the following conditions. However, each individual may experience different symptoms such as:
A respiratory infection
Infection of the nose, windpipe, or lungs
Chronic bronchitis
Post nasal drip
Chronic sinusitis
Diabetes
Gastrointestinal disorders
Liver or kidney disorders
Severe dieting
Dieters may develop unpleasant "fruity" breath from keto-acidosis which is due to the breakdown of chemicals during fasting. Restriction of caloric intake leads to hunger which can lead to a dry mouth.
Factors that affect the airways and cause bad breath:
Nasal Polyps
Foreign bodies
Sinusitis
Dryness
Bronchitis
Pneumonia
Factors that affect the esophagus and stomach and cause bad breath:
Gastritis and food reflux (GERD- gastro-esophageal reflux disease)
Stagnation of food
This comes from this website but unfortunately they dont explain properly what happens then, why do swimmers get bad ears(other than the bacteria) and why does the middle ear gets buggered up with the water in the ear, and why when you do clean your sinuses with salt water like I did this morning, and left a bit of water in htem, as I blew my nose my ears popped!
The closest information I found in there was when they say that all the sinuses aree being balanced pressure wise by the middle ear? But what about how are they linked together? The nwet lacks of answers about the sinus! Help.
I can't be bothered to illustrate this with a picture nor can I be bothered to blog anymore. Bof to blogs. 
