On the second and unrelated point, I also get tired of normal peer pressures and social development being classified as bullying (not that you were). I would also guess that these boys you are speaking of have other environmental issues... no dad, parents that are not engaged, or any one of a million reasons they do not have the skills necessary to integrate or cope with the problem. I would also guess that when you "guide" them, you aren't telling them to "keep dong the same thing, it's everyone elses fault", are you? You are helping them in some way to be stronger, more confident... not come up with excuses or reasons to keep things from changing. That is what we expect from the actual adults and your role is an important one. But still, nothing teaches a young man social norms more effectively than his own peers.
For instance (and this is true).. I can tell my 12 year-old son that he needs to put on deodorant every day and explain why. But he won't... that is, not until a girl at school called him stinky. He doesn't skip a single day now. In fact, he even puts it on a second time before football/basketball practice. It's just the way we are wired
Spot on...I can only guide/coach. Some act on it, others don't...it's not an infallible method.
In my experience, "being there" and having a line of communication open with the young man gives them an outlet or a rescue line they might not otherwise have.