THANK YOU FOR THE QUESTION. Like the fetishes one I'm just gonna answer for my top / most important OC's but if you have anybody in mind I missed you can totally ask again :^)

Shawn: Baseline scent is a cloying, acrid-sweet body odor caused by his hormonal imbalance [excess estrogen from PAIS], mixed with weeks old unwashed sweat, greasy hair + scalp oils, and blood from constant scab-picking and nosebleeds. Now add in the smell of rarely-washed clothes, cheap energy drinks, and expired food. When he hasn't showered [which is often], it becomes eye-wateringly pungent, like a locker room mixed with sour milk and copper. Even after Vadim forces him to "clean up", the smell lingers in his pores.

Harvey: A stale, sour cocktail of cheap bourbon and whiskey on his breath, laundrey detergent, cigarette smoke clinging to tweed, woody / oak-y colognes, and a faint undertone of Brylcreem. There's a lingering note of leather from his car seats mixed with the metallic tang of fear-sweat and cheap aftershave that's been applied too thickly. When he's been drinking heavily, the smell turns sharper.

Abe: Death and old lady. The overwhelming chemical bite of formaldehyde and embalming fluid is permanent on his skin, hair, and clothes; sharp, acrid, and slightly sweet. Mixed with Virginia Slims cigarettes soaked in embalming fluid [creating a weird floral-chemical smoke], dust from the attic, and the faint smell of decaying flesh that never quite leaves him. Underneath it all is this powdery, camphor-and-lavender scent, plus a hint of old-lady perfume and mothballs. He smells like a funeral home that's been lived in for decades.

Randy: Raw, aggressive, and filthy. Heavy masculine musk and unwashed ball sweat, engine grease and motor oil from the junkyard, dried blood [fresh or old], dirt, and the overwhelming sour tang of cheap beer. When he’s been active in the woodshed or on a hunt, he reeks of fear sweat, semen, shit, and pine / earth from the forest. It's an overwhelming, animalistic, coppery smell.

Wilfried: Stale apartment hoarder mixed with taxidermy shop. Strong chemical preservatives and taxidermy fluids [arsenic, formaldehyde, borax], mothballs, dust, and old newspapers. There's a constant sour note of lager sweat, nosebleed iron from anemia, and poorly washed skin. His mother's heavy, cloying old-lady perfume [powdery rose and talc] often clings to him from her constant hovering and clothing checks. Overall musty, medicinal, and mildly alcoholic.

Kenny: Cheap but loud & exotic colognes, an undogly amount of hair products, cigarette smoke, sweat, and semen; the faint metallic tang of blood occasionally cuts through. There's also the artificial sweetness of whatever cheap booze or drugs he's on, mixed with polished leather from his car seats and the general greasy, over-perfumed stench of low-budget porn sets that tends to linger after hard days. "Belial" adds something subtly tangible yet wrong underneath—a sulfuric, smoky, almost ozone-like edge that's barely detectable but makes people instinctively uneasy yet agreeable even if they can’t place it.