That reminds me of an old "Car Talk" call-in. The guy found a fairly large spot on the garage floor under his Toyota. First thing he did was to touch it and it wasn't oily so he reasoned it wasn't motor oil. It wasn't red so he knew it wasn't tranny fluid. It didn't smell sweet so it wasn't coolant. Last thing to do was to put the tip of his now wet finger to the tip of his tongue. Well, he then knew it wasn't battery acid. But the taste was weird.
So what could it have been he wondered?
It was then he saw his neighbors' tom cat slinking out of the garage...
I never ever bring unknown substances to my tongue... now I know why! I also now know why I need to get a UV flashlight...