✔ 最佳答案
It all depends on what the advice is, how it is delivered, and to/from whom it is given.
Mary: You know, George, it might be a good idea to check yourself before leaving the restroom... you're dragging some extra... um... paper."
That may be acceptable and not rude, whereas this...
Mary: You know, George, your hair is a mess! How about using a comb now and then?"
See what I mean?
Have a polite day.
Etiquette takes over where laws end.