This is an interesting point that the OP introduced. I am just lately in my 20s and I have run into little trouble when flying in F or J, but I make an effort to dress professionally and so on. Some would say I shouldn't have to do that, but I would rather have that than the friction. Let's hope none of us younger folks, including the OP, have any trouble any time soon. I think underestimation of the young is a problem in our society, but maybe it's a bit understandable considering how some of the young act.