A friend of mine at Coca Cola, in his report why Tea/Coffee vending machines are not popular in India did conclude:
The fact that tea/coffee contain dairy products (a magnet for bacteria) and is often poured in a dirty glass container does not make it clean. It take 20 minutes of continuous boiling to kill all bacteria. Yet the popular perception is that if the beverage is hot, its clean.
I moved to mumbai recently. The hostel had a tap placed over an ordinarily looking washbasin sink and labeled drinking water. Other residents assured me that behind the wall there is a water purifier (but i could not see it). Hence in spite of all my best intentions the water did taste funny.
Next day morning, I found the water to be cold (as against room temperature the previous evening). Hence the water miraculously tasted OK. All this in spite of the fact that i have no preference for cold water.
Similarly I have seen an amusing habit:
people boil tetra pack milk, then again cooling it before storing.