Would you believe me if I told you the best way is to repaint the wall(s)?
There is another way but it will never produce a totally clean effect:
Heat up the room with an electric heater or with whatever means, just make sure the room is hot. Ideally, when you're heating the room you also have water heating and letting vapor off. That's easy to do in the kitchen, but if it's not the kitchen you can simply bring in hot water from somewhere, the important part is that it lets off vapor so that it sticks to the walls and ceiling (you know, like when you shower and everything in the bathroom gets misty? Same thing).
Once the vapor is in the walls and ceiling, take a dry cloth to them, and rub. But not too hard, because the grime will come off but so will the paint (more if it's plastic, less if it's acrylic).
This will remove a significant portion of the grime BUT it will never produce a totally clean effect, the walls will look like you scrubbed them off and forgot to scrub them good :-) Most of the "nicotine" and such will be off but the wall will have "gaps", you know? Not a uniform clean look.
So, like I said, repaint is the better option.