I think that mostly just has to do with the sheer volume of vapor you get compared to smoke. We, as vapers, have learned to relax our throats and take direct lung-hits, while smokers are accustomed to tightening up on the inhale. When you try to do that with a lung-hit setup, your throat is going to lock up from the surge of irritation.
Haha, it's funny you mention that. I work in a small retail store, so I spend a lot of time in confined, dirty places with lots of traffic from all sorts of people and especially their gross little kids. I usually close up the store, so I touch everything on the shelves at some point in the week. As a manager, I handle more money than anyone else in the store each night, and that's not including times when I jump on register to curb lines. I also have even worse sleep habits than my subordinates do because of the scheduling demands and long hours that come with working on a small management team in a very busy store.
And yet, over these past few years of vaping, I've avoided every wave of sickness that's come along.
Just recently, literally everyone working there caught this terrible stomach virus but me, one after the other. Then, the flu came around and everyone on my shifts had it bad. The office where I count down cashiers' drawers is tiny and stagnant, so when I count down a sick person's drawer with them, I'm not just touching the contaminated money, I'm inhaling the air that they're contaminating by being in the room with me.
I'm starting to think it's vaping that's helping to keep me from catching airborne illnesses. I'm frequently in close contact with people who are sick, but I never catch whatever they've got. It's either that, or smoking just made me more susceptible. I used to get sick at least once during every busy season when I smoked. Who knows? Maybe over the years, I've just gotten too stupid to catch even a simple cold.
All that aside, with vape sharing, it's the principle that bugs me.