Elisabeth, despite all the posts saying nobody will tell you what you should wear, and that there are no rules, you have hit upon how culture works: lots of inchoate rules based on what the key figures and then the majority are doing. So I agree with you there are YLF rules, even if nobody ever states them!
Because of this, I think it's important to approach your own outfit posts with a very clear sense of what you value, aspire to, or simply like, before you start processing other people's feedback. Know that it's human nature that no matter how objective people try to be (and some people do a surprisingly skilful job of this) we view the world through the lenses of our own beliefs and experiences.
I have experimented enough with outfits to know a belt will nearly always make me look worse, that ballet flats stumpify me, that delicate shoes will make my calves look bigger. I know my own preferences enough to know I won't be comfortable in low vamp pumps despite their leg-lengthening properties. I know my own community well enough that when a poster here told me my shoes were too informal for an event, I trusted my instincts and wore them anyway - and got killer ratings from the real life people around me.
I think recognising the unspoken rules is important, otherwise I would have been thrown for a loop and taken advice that doesn't really work for me. I applaud the fact that you do.
Now go out and have fun with fashion, and remember what Vildy said, and also what Una said about shifting the culture by making yourself visible in it (love this idea, thanks Una!) ^_^