I think that rule is posted on the gym wall.
Dudes are just as bad. I watched a "trainer" the other day, through the whole session, checking himself out constantly even during his client's sets. Pulling up his squeezy UA shirt, looking at his abs.
The kooky thing about this is that I think that most of us think we look small or unimpressive, at least no happy with our current physiques. These people have marginally decent bodies but must think they just stepped out of a fitness magazine.
I know I have a good physique and conditioning but am far from sexy pose selfie with it.
I used to be a bit embarrassed doing the Parrillo thing of stretching and flexing between sets. I guess this selfie thing makes me look less wankerish than everyone else?