... and that's how all of the chemicals got discovered.

Great thread over there at reddit:
TIL Splenda (sucralose) was discovered when a scientist accidentally misheard "test this chemical" as "taste this chemical" 


And that's not all: 

"Cyclamate was discovered in 1937 ... Sveda was working in the lab ... He put his cigarette down on the lab bench, and, when he put it back in his mouth, he discovered the sweet taste of cyclamate." "The sweet taste of saccharin was discovered when Fahlberg noticed a sweet taste on his hand one evening, and connected this with the compound which he had been working on that day."
"He accidentally discovered its sweet taste when he licked his finger, which had become contaminated with aspartame, to lift up a piece of paper."
TL;DR: All modern artificial sweeteners were discovered through dangerously careless chemists licking their fingers.

Of course, nowadays it would be unthinkable for a chemist to lick his fingers, but I once heard of a student few years ago that tasted a level teaspoon of the chemical he should analyse. 
After being asked how he got the idea he showed a book from around 1890 which said that you can identify some chemicals (e.g. Acetate or Ammonium) by their taste. Luckily the advisor hadn't given him something really dangerous, but anyways he was quite shocked by that behavior.