I have used one in my room with my parents walking past my door and they have never said anything about a smell. I have never noticed any smell of weed in my room after using a vaporizer.
If you're using a lightbulb vape that you made yourself it might smell a little, but not nearly as strong as smoking. If you have a nice vape theres no smell at all really.
I have a box vape, and it deffently smells. but its not nearly as strong as when smoking it, and it smells completly different than weed. Its almost minty. Unless they have vaped before, noone would know it was weed. It is easily passed off as a minty incense.
of course no matter what you have if you turn the heat up too hot it will burn. Many times in the box vaps my friends do this and it really reeks. I used to use a lightbulb vap and my parents noticed. haha long time ago though
A decent german box-vape (NOT the american-made ones, they suck) usually has a rather light scent. A good friend of mine lives with a roomate who doesn't smoke, and he say's that he just vapes next to his air-purifier, and it completely eliminates the already faint scent that the vaporizer gives off.