I was reading up how people make their own liquids, and one guide reckoned what you mixed with the flavour & nicotine could affect things like how much vapour you actually get, or the hit from inhaling.   From a mental perspective I can see how having really visible vapour helps trick someone into feeling like they're smoking, but maybe if there is a way to reduce the vapour while still having the same physical effects, that will catch on to make it less intrusive?