For some people, anything different or foreign to them is scary. They are used to cigarettes, they know the dangers, the smell, the look, etc. This is something new and therefore, it makes them uncomfortable. They are in essence putting their fingers in their ears and crooning, "I can't hear you" when you talk about it because they would rather remain uneducated and wary.
I try to cut people like this some slack because a year ago I would have seen someone
vaping on an ego-C with a stardust and thought for sure they were doing something illegal and mind-altering. I wouldn't have walked up to a stranger and asked them what they were inhaling. I thought all e-cigs looked like regular cigs but with a light on the end and when I first heard it was water vapor, I thought, "How stupid. No smoker is going to be satisfied sucking in water vapor." I was ignorant. But I chose to educate myself. Some people will be curious and ask about your PV, some will listen when you explain, and some will put their fingers in their ears and hum loudly. The more prevalent e-cigs become, the less foreign they are to the general public, the less scary they will be to these people. We just have to get the word out every chance we get.