Indeed, I confirm you it's hard to achieve because I never really could see that happening...completely.
Yet I remember very quick moments I already witnessed in my life such as seeing an elder cousin of mine shedding tears on his naked belly when we were children, between 7 and 10 years old I'd say, and that triggered me enough to still being turn on by falling and trickling tears over some surfaces, whatever it can be...also at school, some very uncommon times, I saw girls in my classrooms, maybe 2 or 3 in total during my 10 main school years, letting their tears fall on their desk, but they were not my table-neighbours so I couldn't manage to see precisely enough the impact it had over it and it never last long anyway. The first time I noticed it, I was 11, second time I was 16 and the last time I was 17. First time was too distant and unprecise I don't have enough details about it, the second I remember one of our teachers noticed her sheet had water over it when he gathered everybody's sheets and the third I could see her behind me when I just turned back to watch her cry and she was letting her tears drop silently on her arm, between her wrist and her elbow...maybe the sexiest thing I've ever seen in a classroom ! Another time, at refectory, much younger this time I was 10, there was a girl one year older than me I also witnessed crying, silently too, with tears trickling on her nose.
When I became a student, I tried to find college girls able to cry on command and it was a total fail ! The better I could find was only one of them who just tried to do it by cutting onions and it worked a little though, but not that great or at least not as much as I hoped it would...and I mean making a full, compact puddle of tears on a table, once again of course. It was uncomplete and not large enough to consider it like a puddle, because she didn't do with real emotions so I think this why it looked like a bit disappointing.
So yeah, that would be one of my greatest fetishes and fantasms to observe, easily...
Massively shed tears with high innie belly buttons women, these are my favorites things