A healthy gut flora is one that is diverse. 
This diversity comes from a diet of unprocessed foods that is rich in raw vegetables, fermented foods and fibre. Fibre are particularly well researched for their protective effects on the bowel. The benefits come from the short chain fatty acids (butyric acid is possibly the best known but by no mean the only one) that result from the fermentation of fibre and resistant starches by specific bacteria. Those can be in rare supply in the typical processed western diet of high fat, high sugar, low fibre junk. Bowel cancer and inflammatory gut disorders are more common in the western world and generally associated with poor gut bio-diversity and lack of fibre.
Fermentation is how those vital bacteria get their energy in the absence of oxygen (which mostly discribes the environment of our gut). The inevitable side-effect is gastrointestinal gases.
Although we tend to think of farts as smelly 99% of their volume is non-odorous. They are made up of swallowed oxygen as well as carbon dioxide, hydrogen and methane produced by our specific gut bacteria.
Methane has no odour and is only found in about half the population. Methane (from methane producing bacteria) is associated with constipation and Irritable Bowel Syndrome. Farts that lighten up the dorms are not everyone’s claim to fame but could help identify if you harbour colonies of methane producing bacteria. However, I do not recommend this particular testing method at home, an alternative breath test is available.
The pungent smell of flatus comes from volatile sulfur compounds, including hydrogen sulfide, which make up just 1% of its volume.
According to a 2014 study at the University of Exeter in the UK, smelling farts could even be good for you.
Apparently a sniff or two of hydrogen sulfide can help preserve your mitochondria (part of the cell structure of important microorganisms in your body).
In China there are professional flatus smellers who can allegedly diagnose illness and tell you where it is in the body, simply by taking a sniff. Personally, I'd rather stick with colonic hydrotherapy!
High Altitude Flatus Expulsion is a known phenomenon which refers to an increased need to pass wind on flights – not because of the airline food – but because of the reduced air pressure in the cabin.Thank goodness for efficient aeronautic ventilation!
To fart in comfort, without the possible embarrassment caused by pungent smell, you can buy underwear etc. designed to filter the smell of your fart.
Every time you fart you also release your own signature bacteria combination thus marking your space. Apparently we all walk around with our own bactrial aura which we continuously deposit around us. Forensic research is even contemplating analysing bacterial DNA traces left in a room as a way to determine if someone was there or not.
Happy farting!
