>>61215
Certain oils are good for direct use on the skin, rubbing into certain parts of the body (such as muscle groups). Some need to be mixed with a carrier oil as they are quite strong. In this case, you do not need to be able to smell them.
I imagine that even oils for opening the sinuses can be used if you lack the sense of smell. You will just be limited in using these if they are taking the place of sigils for the visual and musical tones for the auditory. Many people discount the value of the senses of smell and taste, but I'm convinced they are one of the most valuable perception complexes that we possess.
I suppose it really comes down to what kind of magickal use you are using them for. Perhaps someone else can give you some more information on evocations and similar rituals. I found certain incenses were more favoured by certain spirits, but I think this was more down to their preference and the smoke was just a visual aid.