Q & A - My bike's fuel efficiency has dropped suddenly what do I do?

Seems like a pretty stupid question , and I am sorry for making you feel like one but the fact that various people all over face this problem and don't know what to do , lessens it's stupidity.
And another fact that yours truly himself asked this question , puts it into very legitimate terms, ahem!
So here we go.
I asked this very question to people who are in business and know much about such things.
Following is summery of what I got -
possible culprits -

1. The brakes.
2. Tyre pressure.
3. Clogged air filter.
4. Adulterated fuel or filling stations cheating you on quantity.
5. Riding style.
6. Spark plugs with incorrect gaps between electrodes.
7. Carburettor.

A very sedate list?Well thats what experts are, starting with basics and getting them right.
Now I go along the list and check for eliminations , Brakes? No the front disc seems to be in love with caliper :) or is it vice versa? anyway time to get it aligned.
*Tyre pressure? checked Ok and same for Fuel, Spark plugs.
*Air filter looked clean and well soaked.Besides If the air filter icon on dash is to be believed then there is no reason to clean it again. But then again I am not leaving any stones unturned and clean it as directed to me.
*Riding style? well now, time for self check.But considering the fact that my bike is only 2600kms old and me for one is not the type who thrashes his bike like anything puts me(or my riding) into safe perspective.
*Moving onto spark plugs.Opened both of them and checked their color.They showed a very dark brown almost black tinge.Indicating that my bike is running on rich fuel mix than necessary.
But the gap in electrode was perfect, so only cleaned them.
And ahh the fuel! yes there are some filling stations that do sale adulterated fuel and also fill in less fuel than your money is worth.So I filled in petrol from 3-4 places and right now settled on ESSAR.

Time for carb.One of the most important part.This little thing can turn things upside down if not set properly and also gives a very visible change in performance when tuned perfectly.
From my observation of sparks I had come to know that the carb was channeling very rich air-fuel mix into engine and that meant I had to control the fuel mix either by myself or by some mechanic.
As some of you might be remembering that I am far away from ProB showroom. And local mechs are such risky proposition, all this made me do it all by myself albeit with a helping hand from Sandeep and Mr.Venkat shyam of autoservice, Banglore(or bangluru...is that right?)

The whole thing as one can easily make out is vastly general and anyone can use it as a guideline on any bike or vehicle for that matter.
P.S.
**Prior to this the bike was returning about 34 kmpl.
**And now after all the trouble (which seems to have paid-off though) the bike recently returned 39kmpl.




-: Phantom menace.The fear is in the eye of beholder :-