There is an important difference between smokers and fat people though. Someone's smoke can enter your lungs more easily than someone's food.
Dang, I was going to say you can't get passively fat then I realised that that is exactly how you do get fat - passively!
Smoke from smokers can damage your lungs but all fat people can do is block the view (don't let them sit on you though!). In either case you can walk round or down wind of them, but if they are really fat, they might take a while to walk round.
Dagnabbit, it is all too confusing. I suggest that everyone treat everyone else and their suicidally stupid choices with respect and we will all get along. Burning Man is all about that, right.
There are good and bad fat people and (relatively-)responsible and irresponsible smokers - treat the behaviour not the affliction, no?
We look at our reflection in a still pool and it gives us a perspective on who we are, but we do not know how deep it goes until we dip into the pool and past the image, necessarily disturbing the surface in the process.