There is a pattern. It is not random.
Of course there is a pattern -- association between substance X and disease D will exist whether
a) substance X causes D or
b) substance X protects against D or its real causes.
Association on non-randomized sample (namely, you didn't pick randomly and assign one person to smoking, another to non-smoking group; they selected themselves into those categories) merely tells you that X and D are in a common web of causes and effects, but the nature of the links within that web must be uncovered by hard science, such as randomized trials or animal/human experiments. That's precisely why I pointed you to a research which performed the hard science investigation regarding the observed association of smoking and rheumatoid arthritis. And the hard science has uncovered that (b) was the correct explanation -- smoking is protective and therapeutic against R.A. (and myriad other autoimmune diseases, as you will find if you care to look, in the thread above), hence people with R.A. in any phase will find it helpful and will self-medicate with tobacco, resulting in the observed statistical association.
This is no different than observing that people who wear sun glasses will have more sunburns than those who don't wear them, even though sun glasses protect you (partially) against sun radiation. It is precisely because of that protection that sun glasses become a proxy for sun exposure, hence for sunburns. Interestingly, there is also a proper dose-response relation (those wearing them more will have more sunburns) and if you were to ban sun glasses, there would be a drop in sunburns (people in sunny regions would dwell less outside in the sun, since it would hurt their eyes more without glasses).
But if you disregard their protective role, as it is routinely done in the antismoking "science" regarding medicinal effects of tobacco smoke, and only observe statistical associations of that kind, you may well jump to the wrong conclusion that sun glasses cause sunburns, as you did about arthritis and smoking (you are apparently unaware of anti-inflammatory effects of tobacco smoke or of the experimental results regarding R.A., such as the one I cited earlier).
Of course, the fact alone that after six decades of antismoking "science" you will only hear about associations on non-randomized samples (smokers have more of this or that disease or other problems than non-smokers), but not about results of hard science (such as the experiment above, or numerous others cited and discussed in the earlier thread), is more telling than anything else -- they are so quiet about the hard science since it always goes the "wrong" way. This pattern is so unusual in normal science that already in 1958, the father of modern statistical methods, famous British mathematician R. A. Fisher noticed it and wrote (pdf; this article also contains a very readable exposition of the sample randomization topic you ought to learn about so you won't be taken for a ride by every junk science scam du jour):
Most of us thought at the time, on hearing the nature of evidence, which I hope to make clear a little later, that a good prima facie case had been made for further investigation. But the time has passed, and although further investigation, in a sense, has taken place, it has consisted largely of the repetition of observations of the same kind as those which Hill and his colleagues called attention to several years ago. I read a recent article to the effect that nineteen different investigations in different parts of the world had all concurred in confirming Dr. Hill's findings. I think they had concurred, but I think they were mere repetitions of evidence of the same kind...
Yet, over half a century later, they are still stuck on making their case using the same statistical argument Fisher objected to in 1958, since the real science doesn't work (for their agenda $$$).
This is a off topic, but the old tobacco thead seems to be locked, so I ask this here: what is your take on polonium in cigarettes? Some sources say that there is a lot of polonium in the cigarettes and when you smoke it is vaporized and it all goes to your lungs. Obviously, this a nasty thought. I dont recall if you have addressed this aspect of smoking in your comments.