From what I can gather when a diver is distressed they will put the mask on their head and reject the regulator, which is what most agencies teach. Since most divers are taught this they tend to look for this as a distress signal. The flip side of the coin is that if you are resting on the surface and another diver approaches thinking you are distressed, then that is a good thing. Someone is looking out and paying attention. When I remove my mask at the surface I turn it backwards so it is resting on the back of my head instead of the front so other do not think I am in distress. Thats the way I was taught. The downside to continuing to place the mask in a position where everyone is conditioned to recognize it as a diver in distress is one day you may actually be in distress and others around you are now conditioned to think you are resting at the surface and not respond to you.