It's really difficult to describe smells when you don't have other cues like names or pictures. Encourage your friends to name or describe what they smell. We don't often compare our sense of smell with others - the game may uncover some unexpected differences!
If you're living with an altered or reduced sense of smell, use the game to get people thinking about what their sense of smell means to them and all the ways they use smell. It should really get them thinking about some of the challenges this can throw up.