It doesn't cause any yellow colouring of the walls etc, but what it does, and the more clouds you make the more it becomes obvious, is that it leaves a greasy sticky layer all over the furniture and mostly on the windows. Not something i am over concerned, simply wipe the furniture at least once a month to prevent it catching up, but the problem is computer components, air coolers to be exact. As the vapor sticks to the fins of a cooling radiator in the computer, it glues the dust particles more rapidly, so i have to clean up my computer radiators like twice as much more then i needed to clean them before, while i was smoking...