Imagine...

Imagine that you're a chemist, and you've followed a standard procedure to produce a chemical that's new to you.  The procedures that you read didn't mention that the chemical you're making has an odor, but it does – an unimaginably foul, evil odor.  So bad, in fact, that it ended up getting you fired.  Now imagine that you had to describe that odor.  Here's a valiant attempt:

But the smell - right at the moment when we quenched (in a hood of course) we were pushed back by the solidity of the reek. I got to know many evil chemical smells over the years but nothing comes anywhere close. With the other stinkers, at least one can imagine what sort of unwashed, putrid, fishy, skunky, human-waste object those smells are related to. But I never encountered anything as nauseating or alien like PhePHMe: The memory is stil with me - the most sickly and sweetish smell of rancid gasoline combined with rotten water melons, with undertones of stale sweat, pig carcass, a hint of garlic, moldy oranges, russian-made aftershave and a cheap household air freshener…  its a whole package, and rather sweet one – like isonitriles or cyclopentadiene but magnified thousand times. A whiff of that thing and you feel that your nose just suffered a stroke and will hopefully die and peal off so that you never smell that thing again.

Not bad.  Not bad at all :)  Do read the whole story – it's marvelous, and you don't have to be a chemist to appreciate it!