I read "somewhere" that there is a compound in cabbage that if you can taste it, you are probably part of the population that doesn't like to eat cabbage. I do wonder whether there is any link between being able to taste the yuck and that means it isn't good for you, or whether it is good for you whether or not it tastes a bit bleh.
There is also the thing that some people can't smell bitter almonds from cyanide.
Another fun scent fact is that hydrogen sulphide, which is pongy eggs smell, and toxic - when you can smell it is in low enough concentrations not to be toxic. When you can't smell it, it has reached toxic levels. Therefore labs working with hydrogen sulphide gas, tend to smell of hydrogen sulphide, just a little, because then you know it is safe - as a final back up to modern detectors.