It can be a very nuanced issue, but a fascinating one.
Since I travel a lot, I also noticed that even in the West, manners, styles of communication and what's considered rude or not can vary to a surprising degree - but that's a whole different discussion.
The best guidelines for me were: adapt to your audience/company and practice "active" compassion/empathy.
For instance, in somebody else's house I would say "can I have some water (please)?", at home neither of us minds if we just say gimme some water etc. So as a first step, keep in mind the personality and the type of relationship you have with whomever you're interacting with, some people are more sensitive, formal, easily offended etc.
Speaking of zits (btw Magna, at that age is usually hormonal and scrubbing will make the problem worse) - my son is lucky and still has china-doll skin, my daughter, poor thing, not so much. My first inner thought was along the lines, get over it, it will go away, you won't even remember in a couple of years. Then I stopped to think and remembered how intense everything feels at that age. How it might not necessarily go away and even if it does, kids can be nasty and a hefty blow to her self-esteem at this age might actually do significant harm.
This part of actively trying to see things from someone else's perspective needs constant practice and can be tiring. I put in different degrees of effort depending how much I care about someone and how important the relationship is.
I don't do any roundabout and coded small talk though, it gets on my nerves and find it useless and am polite but use zero fluff at work. My team actually gave lots of good feedback to my boss for being the only lead that keeps meetings short and to the point. In certain situations, bluntness and precision have their value.
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"Facts do not cease to exist because they are ignored." Aldous Huxley