i would agree as so far as visually it shouldnt be seen, thus "accepted" to be an example.
i dont think smokers, Staff or Cadets, should be seen to be smoking in uniform, at the very least "hidden out of view"
i would not expect any Staff member to be freely drinking in front of Cadets, in my experience this is only done in seperate quarters away from Cadet eyes.
as such both examples are not readily seen, and done so in a environment which can be controlled
the size of someone's waist is however always visable and thus a different topic.
whether on a Standard Parade night, a weekend exercise, public event or formal parade the size/shape/visual health of all are there to be seen, and thus an issue of not just an "example" being set by a role model (staff) but has implications on the public opinion at the same time.
Edit: wdimagineer2b beat me to it!