Only if you have something your hiding. I don't mind explaining it to people, and more times than not, they think it's great, and maybe they will purchase one for themselves.
I usually follow the same rules as smoking. With all the unwanted attention vaping is get from some groups, I don't want to give them something to complain about, even if it is unwarranted. Although I will say I took my ego into the hospital with me when I had rotator cuff surgery. I knew they were going to keep me overnight since I had a triple bypass not quite 6 months before. I was stealthy in my hospital vaping and they never knew, it also kept me from having withdraws.
I use mine in public, but I am respectful about it. Regardless of it is safe, or not for second hand, it's just impolite to pull it out in a movie theatre, or restaurant and causes unwanted attention.
This guy from a Dutch forum was just openly vaping in his hospital bed. That was pretty funny to see a picture of him vaping in his hospital bed.I was stealthy in my hospital vaping and they never knew, it also kept me from having withdraws.