My experience has ranged from curiosity to indifference, haven't yet had any negative run-ins, yet. Not even taking my Provari through airport security two or three times a week, I've had a few ask what it is, others already knew, like today the TSA guy looked at it in the bin on top of my coat and asked, "is that an electronic cigarette?" I replied in the affirmative, he pointed it out to the lady running the scanner, and she simply said, "yeah, that's what he wants us to THINK it is," laughed at her little joke and I passed right through!
FYI you're better off putting the larger tube or box
mods right in the bin and out in the open, prepared to answer the question, than trying to stash it in your carry on, found that out and thought I'd share!