Yes, the Malaysian contingent of my in-laws are certainly a lot less shy about sharing their opinions than the Anglo ones.
Oprah, is your SIL the sort of woman who happily comments on your life? I assume you don't have children so maybe you can't tell yet (I mean, a lot of people only get opinionated when children are around, IYSWIM) but do you get a sense that she accepts comment or criticism generally?
It is tricky. The soaps and the hidden food and the dirtiness all seem to paint a picture of someone who isn't coping.
And I do agree that teaching kids that age to look after their own hygiene isn't that straightforward. I know that's the age where a lot of girls get into using stinky perfumed deodorant but don't necessarily shower every day, put on makeup but don't wash their hair, etc. And the boys do the same stinky deodarant thing but it never overpowers the Feet smell. I think it's worth doing, but I can totally understand why they haven't done anything about it themselves yet.
I have a good friend who was never taught properly, and who claims to have a bit of a phobia about showering. She's 28 now, and her hygiene is fine, but in her early twenties she still didn't clean her teeth often enough (and she was a chainsmoker, blech), would shower once a week, her hair was always greasy and her clothes never washed. She'd spray the underarms of her tops with deodorant to cover the fact that they'd been worn several times. Once, she moved from one side of the country to the other by taking a 72 hour coach, and when I saw her three days after arriving she still hadn't showered.
What snapped her out of it was her partner laying down an ultimatum, and also agreeing to keep her company while she showered - just being in the room chatting to her helped. But this was an intelligent woman who held down employment and a relationship, and she smelt. She had just got used to it for so long, she had no idea the rest of us could tell.