Interesting topic, and I hope folks won't be too shy or be too worried of judgment to explain. I know we once had a similar post, though I think it was more a "what's your fetish?" than why? thread.
Visual ASMR: basically I LOVE seeing textures...I don't straight up jill off to it, but I guess you could say seeing pleasant texture puts me more in the mood. Anything shiny is a big one for me. Wet look, soft textures are great too.
I have no idea where this fetish came from. I assume it's probably related somewhat to a hot art teacher I had growing up and teaching how to create drawings and such to look realistic through texture.
I enjoy wet n' messy to some degree like the visual of wax, whipped cream (pretty much only white or clear is my thing) All sorts of fetish clothing can work with this kink of mine.
Big ones for fetish clothing are:
Aprons (doesn't have to be naked underneath, but I like it regardless of gender),
Catsuit-I watched batman growing up, so that happened. I have a thing for gloves which might come from stuff I watched or liking the feel. Who knows?
Gimp/Rubber dolly-I blame the green ranger.
Headphones/earmuffs- Something cute about them to me especially if the person is lost in their own lil world listening to music.
Jodhpurs-I don't recall exactly where this came from for me, but love them on men or women.
Maid outfits-Maid from beauty and the beast is the first that I remember.
Zippers-I think it simply automatically is associated with me as clothing being unzipped. Even without the zip sound I like the look of zippers with clothing.
Backs/shoulders
I find them incredibly sexy. Not sure where exactly this started. Gonna go with Jessica Rabbit, but no clue of the exact origin. I find men's backs and shoulders ridiculously sexy too, especially with broad shoulders.
Bath/shower
(see visual ASMR)
Big tits
I find this one common. I have big tits too. They're great...Like I can give a lot of examples of women with huge tits that coulda caused this, but we may be here for a while.
Bondage/BDSM
Prolly somewhat to do with texture depending on props involved. I think a lot with these are very "grounding" and intimate in the sense of making the people involved feel more in tune with what is going on since much required both to be focused on the other's needs.
Chewing-I like brats and the image of a brat chewing/blowing bubble gum. Can work with regular food chewing, but prefer gum.
Exhibitionist- I figure this stems from the fact that I grew up sheltered, and in the middle of nowhere but *shrug I also like looking at public/outdoors porn so there ya go.
Embarrassment fetish- I find people looking awkward and embarrassed really hot. Extra points if they blush. Roleplays don't work well here for me. Has to be actual awkwardness. I have a thing for redheads and pretty sure it's mainly due to the visibility of blushing.
Fingernails-Love manicured nails. I'd do mine more but it's often hard to um...work with. Still love the look. Also I love the feel of fake nails.
Flexibility/stretching-My overly conservative mom forced me to do gymnastics and dance class for decades. I hated everything but that part. Thanks mom. No really. Leotards, long legs and legwarmers/nylons are big with me too and likely due to these classes.
Footsie and tiptoes-Not much into feet except with these two. I think both seem very intimate and cute.
Hentai- I turned on the internet. There's your origin.
Strap-on play-Um. I had sex with someone multiple times and it involved a strap-on. It was pretty awesome, so we filmed it.
Unnaturally colored skin- Usually this is a females only thing for me. Prolly involves the twi'lecks in Star Wars. Life goals-film myself with banging rubber clad, Twi'leck(s) with a strap-on while being called daddy.
Hips-not into ass specifically but rather hip bones and side view. I blame my crush of Esmeralda from Hunchback of Notre Dayum those hips.
I find kissing scenes really hot. I feel this one is fairly common.
Tats and piercings dyed hair- love alt looks though I have none of this look lol. I dunno. Might be an opposites attract sort of thing.