I've been close to a few other vaginas in my time, and smell really varies. IME being too hot, sweaty, not had a chance to shower etc can change the smell. And it's really distinctive.

I agree it's often teenage lads with no experience trying to make themselves look big. It's sometimes just derogatory, making nasty remarks re women's vaginal smell can be a sign they don't like women. It's a really crass thing to focus on.

Either way I'm not a fan.

A lot of it is just purile men being 'funny' and not realising how much it can hurt people. However it is a real thing for some people but TMAU isn't the main reason why smells like that can be common. Most of the time it would be bacterial vaginosis which, can be caused by being overzealous with hygiene, affecting the natural flora balance and resulting in an establishment of bacteria that produce trymethylamine.

Its cruel because people think that the cause is poor hygiene and further over-attention just causes it to persist when it actually needs treatment with antibiotics etc.

Boys with no experience trying to lie to their friends by repeating what they heard from other boys with no experience. Going back to the 80s at least it was all over the schoolyard. Maybe it becomes like some sort of automatic response at some point. Even when it stops being funny it still gets repeated.

I think a lot of men are simultaneously attracted to and grossed out by vaginas. They don't have anything equivalent on their bodies and so they may assume the natural odor of a healthy vagina is actually unhealthy or indicates bad hygiene. Many of them seem suuuper ill-informed and yet opinionated about how women should clean themselves. I also think it's just a really easy way for them to disparage women.