I'm of the personal opinion that I have a bad sense of smell. If I could do it, you could too.
A lot of the smells require you to experience it in order to relate. I don't recall them forcing us to smell everything back in school. But, the smells are super helpful.
The burnt chocolate one is interesting because I have heard some folks say it smells disgusting. To me, it's just a light cocoa smell. So, everyone's mileage varies.