I'm not a smoker but a good friend of mine has an ecig which doesn't even resemble a fag. For starters its black, on a chain round his neck, and the mouthpiece is clear.
The way he 'smokes' it more resembles him suckin a lollipop, with the whole unit in his hand, with the mouthpiece at the top of his closed fist poking up.
If u held a regular ee garette (nice) in the same way, and it was a cold day, or night, surely it would be impossible to see the difference between vapour and someone's breath.
It would also eliminate confusion between different lights comin out at the end.
In my experience its easy to see the difference between vape and smoke, as vape dissipates quickly, like your breath while smoke doesn't, plus vape rarely smells, and when it does, it smells nothing like tobacco.