My general rule of thumb with vaping is this: If you wouldn't fart there, don't vape there. That has kept me in good stead for a while now.
If I am walking down the road and vaping I try to blow it in a way it isn't going to go straight in someone's face. Just like I wouldn't fart in someone's face. Occasionally things don't work out and the wind blows it a way I didn't expect, and if it makes sense I will apologise (eg if you are standing at a crosswalk and the wind changes direction and blows a big cloud in the person next to me's face, I'll obviously apologise for fumigating them). Otherwise I will just keep on trucking.
It's general common sense. I would also assume that it is common sense that comming into a vaping thread to whinge about inconsiderate people is not super productive. All for it if you want to have a discussion with us about something to get our perspective though