Certainly, different people's smoking habits can effect whether it's smelled on their clothes, in their house, vehicle, whatever. As can other people's sense of smell. Some of you may not smell it on those around you, but there are likely others who can. The smell can linger. I used to be a contractor repairing repossessed houses. Many of them smelled of pot. The worst was actually a house that had been vacant for 2 weeks and had no furniture inside for the smell to linger on. We replaced the carpet and linoleum, cleaned, febreezed, and used odoban (a strong deodorizer). You could still smell it. Our rep finally had us paint the entire house and we were able to get rid of the smell. As a PP noted, an 11 year old child noticed the smell in her grandmother's home while the grandmother was not actively smoking. The smell does linger, and especially so in places without a lot of ventilation, like a house.
Also the effects of breathing in the second-hand smoke have been compared in several studies to that of cigarettes. It continues to baffle me that while so many people are taking a stance against smoking cigarettes in public places due to the effects on non-smokers breathing it in, so many people are all about legalizing recreational use of pot, which can then be smoked in public as well. Breathing in any kind of second-hand smoke, cigarettes or pot, is not good for anyone. Some studies have found pot present in non-smokers who are around those who smoke, and if those around them are smoking a good bit of pot, the second-hand smoke has been shown to cause mild impairments in motor tasks... And this is just from a contact high, without even smoking it.