I think some guys just have a problem with this. If you can't do it without a pipe, you're probably not going to do it any easier with a pipe. I tried and tried to show a mouth-breather how to do this at the B&M one day. Some guys just don't have the natural reflexes to breath exclusively through their noses throughout the day, and when it comes to exhaling out their noses while by-passing the lungs is just impossible.
Mouth-breathers, are people who just always breath through their mouths, without being able to just reflexively use their noses. I am not sure why this issue exists, but people like Nicholas Cage are mouth-breathers. Watch him closely in his movies. He never closes his mouth for an extended period of time (giving him a slack-jawed look, or hangdog expression), and it also gives him a unique voice. But, ultimately, they drive me nuts, because you can hear them breath. Yeh, little things like people breathing gets on my nerves, ha ha.
But, when showing a guy how to push the smoke out of his mouth through his nose... he just never got it. I attribute this unscientific bit of data sampling to him being a mouth-breather. My next unscientific bit of exploration will be in the realm of oral pleasures. Do mouth-breather chicks... eh, I don't want to reveal the happy ending. Stay tuned.