I've found that the bigger and louder your device is, the more likely people are going to ask you what you're doing and the less likely they are to deny you of vaping or give you those cold looks. However, with the ego's and such, because their so similar in shape and size to a cigarette, people tend to see what they want to see and then judge you accordingly. I did have a couple of instances where this wasn't the case, such as zoo's or theme parks where smoking or vaping is strongly prohibited except in smoking areas. Other than that, I vape at the mall, in restaurants, at the bar, at best buy, etc. and no one's been the wiser. As long as you're not blowing out chernobyl sized clouds then for the most part you're in the green.