It's very toxic and leaves a powerful "imprint" on people who walk through even small amounts of the mist. The smell literally last about as long as weed does, and no matter what the smell is, it's still unwelcome indoors.

No one who cares about their health wants you to vape and walk back indoors with a device carrying so many times more nicotine than should be allowed.
It's also your breath, and some people tend to put our mouths were others don't want to go near. The mist enables the germs to cling to it and remain air born. It's a health hazard.