Once, I was with a friend of mine at a bar. He was a recent convert, and we were both vaping and drinking by the counter.
So, this girl, known to him, approaches the counter to ask for a coffe and tells my friend "Have a cigarrete instead, David. I would be BETTER for you". This, with a lit cigarette in her fingers.

He asked her why exactly she believed that. She told him she had heard some news that stated "nobody knows what's in those".
My friend David pulls his bottle from his pocket and reads out loud the list of half a dozen ingredients. Then asks her if she knows EVERYTHING that is coming right now from her cigarette smoke. I did not like her attitude either, so I simply told my friend "That is way too much to ask, David. Ask your friend if she can tell us at least the name of the sixty-or-so carcinogens..."
Well. This chick had a tantrum. She was offended because we were "making fun" of her, when all she was doing was warning us, in good faith, about the "unknown dangers" of e-cigarettes. And that we really should not simply join any "new wave" without "thinking about the consequences".
This was a "new wave" to her only. She did't know e-cigs even existed before she heard "the news". I was vaping at least for four years back then. Four years reading positive studies that convinced me to make the switch in the first place.
And all of a sudden, someone who currently *smokes* becomes a vaping expert just by earing ONE biased piece of junk news. And gets offended because an *ex-smoker*, *long-term* vaper makes fun about her very opiniated, yet very mis-informed attitude about vaping.
Because this know-it-all, who refused to listen to reason when I tried to explain it to her, was "concerned" about our health, and all she wanted to do was "warn us".