I think burnt popcorn can have a coffee smell.
And baking soda toothpaste tastes/smells like fish, but when you rinse your mouth is sparkling fresh. Weird.
The coffee thing . . . I’ve never heard anyone say that. Now, in my case, I’ve noticed a tuna fish smell - but it’s in my 9:00 piss, if I’ve drunk a lot of coffee. I first noticed it a few years ago - mornings when I have a bit more coffee than usual, after its diuretic effects kick in - bam, tuna piss. So apparently whatever that tuna-smelling chemical is, it survives the digestive and excretory systems unscathed.