There was this book I read a bunch of decades ago and I didn’t like it. I had to read it for A-level English, so presumably I answered questions on it, but I don’t remember the story except that there were silly rich people who kissed people they weren’t married to or didn’t intend to marry. It made no sense to teenage me.
The only scene that sticks in my memory is the one where the silliest woman (I think her name was Rosemary) returns to her room to do up her face and hair, and takes a long time to notice that there’s a dead body lying on her bed.
There’s a paragraph or so where the author (third-person omniscient) speculates on what causes us to look around when we have a dead body leaking blood from its wounds behind us. Is it garbled micro-reflections in metallic objects dropping subliminal clues that something has changed? Is it a sixth sense? 
Well, Margaret Atwood would have made it a sixth sense, and the departed soul would have spoken—telepathically of course. JK Rowling would have made the corpse transmit a pain sensation. Dan Brown would have mansplained the scene into oblivion with heavy, info-dump dialogue. Agatha Christie would have made Rosemary finish her face and leave the room without a qualm, thus framing herself as the prime suspect. And so on.
Nobody, almost nobody, would have Rosemary detecting the scent of blood and body fluids. Are famous authors all heavy smokers, deadened to all smells except nicotine? If I had a dead body anywhere in my house, my nose would tell me.
Culturally, I think we’re accustomed to relying too heavily on our sight and hearing, to the detriment of our awareness. We read the Best Before dates instead of using our noses. We share photos of food on social media, as though its presentation was the whole point. Generations of horticulturalists have bred roses for colour more than for smell. (Why? Why would you do that?) And authors have tapped into readers’ visual/auditory imagination without realising that smell is more fundamental, more closely connected to memory and the visceral unconscious.
There is more than one sense of smell, BTW. There are things you can detect consciously, like blood and old-fashioned roses. There are also things you’re not aware of, but which regulate your physical responses. When my children were small, on a long car journey I would always feel myself hit by a wave of sleepiness. Then I would look round and find that one of my sons had just that moment fallen asleep—and had, presumably, given off synchronisation pheromones. There was one time when we visited people whose baby had never yet stayed put through the night, but with my son in the room she slept like a log. Babies control us (and one another) in more ways than we know. Smell controls us in more ways than we admit.
I’m arguing for giving the sense of smell its proper place in stories. I don’t do it enough myself, but here’s a little snippet of a story in which I did use smells to raise an uneasy feeling. A Country Cottage, first published by The Horror Tree/TWF, 2020.
Mrs Kennaway pottered in her garden on fine mornings, a small, tidy-looking figure always in floral pinks. Her eyes, pale-grey and slightly dazed in expression, seemed to look past you, but she would pass the time of day in a mildly plaintive, faraway voice. She would offer a newly-potted flower or a home-baked scone, or invite you in to share a pot of tea in delicate china cups and saucers.
A smell of fresh baking seemed always to fill her cottage; and under that, the clean-swishing scent of laundry—and below that again, a hint of lavender, thin-bluish as a distant plume of wood-smoke. You would have to have a keen nose indeed to discover, beneath it all, the iron tang of blood, old blood, impure like the fluids of an uncleaned wound.

