I don't see how bias affects the results on studies about whether or not second-hand smoke is harmful or not. It might influence them, but I can't imagine it's going to change the answer from a no to a yes or vice versa.
And I don't mind them policing it either. It's a rather unpleasant habit that shouldn't be allowed to affect non-smokers. Smokers can smoke all they want, just do it where I don't have to inhale it.