Guess I can post this here.
In Touhou, stench and scent of characters is actually something brought up (arguably, the comments are "just insults"; I'm interpreting them as blunt truths). Some things to note:
-Suika smells good according to both Yuyuko (who was attracted specifically by her scent, which she liked) and Cirno (though Cirno may have been talking about her sake). Her name also implies that she smells nice (gathering fragrance), given ZUN gives characters meaningful names.
-Mamizou reeks of stanky tanuki stench and tobacco.
-Most animal youkai have an obvious odor.
-Orin isn't said to stink, but she's constantly carting and burning corpses, and that probably doesn't help anything.
--Minoriko smells delicious, like sweet potatos. She also mentions that gods take very good care of there smell in general.
-That said, Shion stinks.
-This suggests Joon does not stink, but she does smoke so maybe this was a case of the pot calling the kettle black. That said she is known to easily get into peoples' good graces. Personally, I believe it's likely one of her race trait bonuses as a god is that she can't smell bad, but that is FLAGRANT headcanon.
-It's not canonically KNOWN that Tenshi smells good *specifically*, I think, but everything suggests that she constantly smells divine along with the plethora of other free benefits she gets just from being a celestial. Celestials are canonically perfect.
-Similarly, we can infer Yuuka is likely to smell like flowers.
-Marisa may or may not smell. She's often rolling through the woods and mixing chemicals, and her house is a fucking mess, but she enjoys taking baths.
-Patchouli is known to bathe, and her books are warded against water damage (among other things).
-It's probably safe to assume that Eirin, Kaguya, and Mokou do not *themselves* smell because their bodies are in eternal states of "perfection", and any negative changes are immediately rectified. Their clothes could smell, unless Eirin's elixir magically works on ones outfit as well (Mokou revives with it on whenever she's obliterated, but who knows).
-Fairies could be similar because they're also a kind of "eternal", but we only know for sure that they revive after death, not necessarily that their bodies always stay the same. That said, none of them are ever seen bathing, none of them have access to baths, and yet "fairy stink" is NOT something other characters complain about, despite openly complaining about animal stink.
-That said, Eternity can skunk it up with her weird antennae at least.
You can probably assume most characters with homes bathe, but this is only based on what I'm certain we know.
While oni may be smelly in myth, it doesn't seem they smell in canon necessarily. Reimu, who is quick to complain about how much another character might smell, likes Yuugi and Suika. Marisa also hangs out with her regularly. Feel free to mention anything I forgot.