What? Don't look at me like that, this is a serious question! Kind of like how a demon's disguise could be undermined by the scent of sulfur what signs would hint at the presence of a celestial?

Well I just googled "smells associated with angels", now theres a sentence I would never have thought of before today!.

Apparently there are some scents split into: Flowers, Scents associated to loved ones (such as favourite perfumes), scents associated with places (dew covered meadow) and food.

Some examples given were:

• Frankincense: spiritual enlightenment
• Rose: comfort or encouragement
• Grapefruit: gratitude
• Mint: purity
• Cinnamon: peace
• Spruce: joy

I dunno, it depends on the kinda celestial you feel like running, but if we're going all benevolent NPC then I'd make them smell like my character's favourite comforting scents. Then probably have everyone go round and contribute that

This is also a copout tho cuz I can't think of a universal smell. Maybe if they're more the holy avenger kinda celestial then they smell like woodsmoke

Quote from Agent_Grey >>

What? Don't look at me like that, this is a serious question! Kind of like how a demon's disguise could be undermined by the scent of sulfur what signs would hint at the presence of a celestial?

The "brimstone" smell is associated with demons/devils/fiends in lore outside the game.  In those outside lores' "world building" there is no table of equivalency granting "celestial" beings a balance olfactory tell parallel to the brimstone.

In a lot of lore, celestial beings don't have a lot to hide, so radiant auras or halos are often associated with them in visual art, "heavenly" musical affects (one could play through thaumaturgy), etc.

I supposed in an edge case you can say one smells like Teen Spirit.

Quote from MidnightPlat >>

I supposed in an edge case you can say one smells like Teen Spirit.

 Only Kurt smells like Teen Spirit. 

To the OP, in non-D&D lore angels in disguise often appear as regular folks. Travelers, sometimes beggars. Part of their appearance is a test to see how righteous a person is in their dealings with people of lower social status. In those cases, they usually don’t have a tell. But if you want them to, for world building, go for it. Just be consistent, and have a religion check DC in mind if your players ask about the stranger’s smell. 

Well, if you go more literal on the whole “celestial” thing and think “from the stars,” according to astronauts space smells like gunpowder.

I think the closest you will get RAW would be the fluff description in the paladin divine sense ability.

"The presence of strong evil registers on your senses like a noxious odor, and powerful good rings like heavenly music in your ears. "

So you smell demons and hear celestials :)

Other than that, you could have celestials smell pleasant whether that would be fresh air, scent of pine trees, clean air of an arctic winter, freshly mown grass, various spices or sugar/sweet, or whatever else would be entirely up to you as the DM.

However, I don't think any particular difference in scent would be noticeable without a special sense.

I think devils smelling like brimstone is their own thing. Celestials should have their own thing rather than a derivative version of someone else's thing. 

Maybe Celestials don't cast a shadow. Maybe their reflection always shows their true self. Maybe in intense moments you can see the shadows of their wings (is that a dated reference now? How long has it been since Supernatural was good/relevant?)

Papaya?  Also called the “fruit of the angels” by some explorer navigator named Cristophorus Colombus  because it was very delicious, sweet with musky undertones

Innocence.

Joy.

Harmony.

Peace.

Welcome.

Kindness.

Terror.

Justice.

Horror.

Bird poop.

That stuff you once pulled out of the fridge and had no clue what it was and then you opened it and your whole life flashed before your eyes.

It is going to depend on the nature of your setting or the place they exist in, but mine tend to be Angels, Malakim, and Valkyries, and they smell like Authority, Vengeance, and Apples.

No idea why Valkyries smell like apples. I keep asking and they just laugh and say "go die a worthy death".

Quote from David42 >>

I think the closest you will get RAW would be the fluff description in the paladin divine sense ability.

"The presence of strong evil registers on your senses like a noxious odor, and powerful good rings like heavenly music in your ears. "

So you smell demons and hear celestials :)

 

       What is "heavenly music" is very subjective, though. Just cause some angels are usually depicted as playing harps, that doesn't determine anything whatsoever in a particular campaign world.  Or maybe a particular paladin hates harp music.

        I'd offer that celestials smell like a buffet restaurant - because what other activity is most associated with heaven besides being able to eat what you want and not gain weight!

Fresh baked Chocolate Chip Cookies

Milk and honey?

They smell like the dust whirled up from a sunlit window sill.

I would imagine that celestials just smell like fresh air - an area devoid of smells, the air pure around them. You'd notice them if the fish stall you shop at only smells bad until you step up to buy, and that tells you the shopkeep is a celestial.

Fresh baked bread. I thought everyone knew that? oO

Vanilla flavored Bubblegum

The bakery section in Costco.

Your 2 month old.

A new car.

Sunrise after it rained all night.

The first cup of coffee.

Fresh-cut spring flowers strewn across a babbling brook with a hint of lemon.

My aasimar light cleric smelled like the sea, with a hint of campfire in the background.