Re: Must.. have... proper... coffee!
When I worked for BT Syntegra UK Ltd. (subsequently absorbed into 'Big BT'), we had free 'coffee' and 'tea'* from a vending machine. It tasted really horrible, so lots of people ignored the free stuff and brought in their own provisions and mugs, myself included.
One Monday (I always took my mug home for a proper wash over the weekend), I had forgotten my mug. Aha! I thought, I will get one free coffee from the machine and re-use the plastic cup for my own, better tasting coffee. This was how I discovered that the foul taste was the plastic cups, not the tea or coffee. I never did find out what poisons the plastic cups leeched into the hot drinks - anyone care to enlighten me?
*(Well, something almost but not quite entirely unlike tea, actually, but you get the picture.)**
**Obligatory HHGTTG reference whenever 'tea' is mentioned.