Is there a neutral word for an olfactory impression?

Solution 1:

The results in this Google Books Ngrams chart seem to imply that the terms, the scent and the smell are the most used.

In order to ascertain how neutral these terms were I selected the following criteria.

• smell of *
• scent of *
• smell of the *
• scent of the *
• smells good
• smells bad

The asterisk represents any word that follows the last term which Google Books has a record of.

Link to Ngrams Chart

Judging from the results, it appears that the verb smell is more often associated with the adjective good than with bad, at least in its written form. However, if one notes the different terms used with smell of; smoke, death, burning, and blood along with fresh, the sea, the earth, etc. it is clear that both pleasant and unpleasant odours are collocated with smell. Whereas the noun scent tends towards positive collocations such as: roses, pine, fresh, the sea, jasmine, the flowers.

Consequently, the OP's choice of Scents & Smells for her proposal appears to be a very sensible and objective decision.

Solution 2:

I think odour ( or scent) is the more general and neutral term, to convey specific olfactory impressions you have to use other definitions such as fragrance, aroma or malodour for instance:

• is caused by one or more volatilized chemical compounds, generally at a very low concentration, that humans or other animals perceive by the sense of olfaction.

  • Odours are also commonly called scents, which can refer to both pleasant and unpleasant odors. The terms fragrance and aroma are used primarily by the food and cosmetic industry to describe a pleasant odor, and are sometimes used to refer to perfumes. In contrast, malodor, stench, reek, and stink are used specifically to describe unpleasant odor. sometimes the term funk can be used to describe unpleasant odour.

Source: www.wikipedia.org