If you go around capturing smells from different places, the most prominent are probably of things that smell. The same goes for our childhood scent memories.
Why is it, then, that when you want to evoke an image of a setting, you sometimes add in fantasy notes of visual components that may not contribute to the actual odor of the locale?
Think back to a place you love.
Is it only the smell that comes to mind?
Surely not; there are other senses, textures, and spatial arrangements at play, and these create the memory as a whole. To reconstruct the scene now using only one medium—scent—would require translation of the other sensory components. And because it’s not a direct, one-to-one exchange, it can become a scenario where you need several common words in one language to explain the meaning of a pithy phrase in another.
Hopefully, by the end of the process, you get a rough sketch of the essence of the place and time.