maybe the room already smelled horrible before vaping even came into the picture? lol.
this is largely subjective of course. I dont think vapor has much of a smell to it, and i dont think it lingers either. In my experience, if theres no combustion, the smell stays around about as long as the visible cloud of vapor does. So, of course, if you have multiple ppl blowing out vape hits in a smallish area w/o much of any air flowing in/out, your going to get a bit of a cloud. Sometimes you can't really see it either. I remember one day i was vaping with the blinds closed and the sun was streaming through a little opening in them and in that stream of light i could see vapor swirling around a good while after i let a hit out, even though it wasnt visible outside of the light beam.
I vape in a non-smoking office environment every day after my co-workers leave. I've had ppl come in shortly after vaping and no one has smelled anything, but it was just me, and i only took about 4-5 hits over the course of as many minutes. Then again, I've had someone surprise me WHILE i was taking a hit from my launch box, and I slowly let the hit out as i spoke to them and they didnt even notice.
In general, i dont think ppl will notice the odor unless they're trying to. What i usually try to do is heat up some food or something right before i vape, that way ppl cant smell anything past the aroma of a nice hot dish. Or vape in a smoking area, ppl will never smell it past cigarette smoke or butts. Vape near an open window or in a bathroom or somewhere with good ventilation if you're still paranoid. Wait longer between hits to prevent too much from building up. If youre vaping in a room w/o open windows/vents, try blowing your hit straight up maybe (ive found it to work well in rooms with higher ceilings at least... but dont do this at, say, a movie theater since you'll blow it through the projected light and it will be pretty visible lol).
always err on the side of caution tho of course. different ppl have different levels of olfactory sensitivity (cigarette smokers usually can't smell crap past their own hair/clothes), some ppl know what weed smells like some dont, different environments have different smells which may or may not work to blend/cover up the smell of weed. In general though, WHILE you're vaping worry about the smell - but by the time you've shut your vape off and it's cooled down, the smell should be gone too.
if this is the case, listerine strips work well 
. That's a buzzkill.
