There are some people who think that since the research on e-cigs indicates that they are likely a safer alternative to cigarette smoke, that that means e-cigs are 100% safe. There are others (who tend to be assholes anyway) that think because the law only prohibits smoking that that means e-cigs can be used in any public space with impunity. I know that the e-cig communities online, generally do not advocate this kind of behavior. Honestly, the worst way to go about winning people over and selling them on the idea that e-cigs are a much less harmful alternative to smoking, is to blow vapor in their collective faces. In any event, blowing smoke (or in this case, vapor) in someone's face is pretty much always a challenge of some kind, unless of course, it is by accident.
If a person has been rebuffed and refuses to let up even if they've been told that their advances are unwelcome, then they're the asshole. I knew a guy who was on his last strike for assault before getting into serious trouble with the court. He had a history of anger problems and was generally a very physical guy. I don't at all mean to imply that he was an abusive type and to my knowledge he is not. Anyway, he used to go to punk shows with mutual friends of ours and at one of them (just after that "last strike" warning was issued and not a great place to go, all things considered) he got into an argument with a girl from the scene and apparently tried to get out of the argument. He'd been in an anger management program and was doing pretty well, but then she went and tried to stub her cigarette out in his eye and just missed by about a 1/4 inch. Now, this guy was about 6'2 and 235 lbs. of pure muscle. I can't blame a guy for reacting to a burn, or trying to keep himself from possibly being blinded, but I am sorry that it had to happen between him and this particular girl, who I was told was about 5'2 and maybe 100 lbs. Anyway, the story is, the cherry hit the skin near his eye and his right hand smashed her face and by all accounts, fucked her up pretty badly. Again, I wasn't there, but from the accounts I heard, it sounded like she was being the asshole.