I don't hate smokers, and I'm not going to be extreme enough to say that smoking is dangerous to anyone around a smoker. However, smoking can be incredibly irritating, and a lot of smokers don't seem to notice or care since "they have the right to smoke."
There's an ordnance in place where I work that people are not allowed to smoke within ten feet of the building's doors. In order to encourage smokers to stay away, picnic tables and ashcans are set up the appropriate distance away. How do the smokers respond? By dragging the tables and ashcans over toward the building and gathering around the door, ensuring that anyone entering or exiting is forced to walk through a cloud of smoke. Also, during the winter, since it's too cold outside to smoke, people tend to just smoke in the bathrooms; this is not only annoying to people who don't like trying to use the bathroom in a haze of smoke, but also illegal.
At another job I used to have, one of the employees was a heavy smoker. Since our manager was also a smoker, they seemed to have a sort of understanding of "the habit," and so my coworker was allowed extra breaks beyond the usual allotment so she could go outside and have a smoke. I asked for an equal amount of break time, since I would've loved extra time to wander down to the nearby mini-mart for a drink, and I was told that I couldn't take any more breaks because I didn't smoke.
Essentially, my experience with smokers as a group has led me to believe that many of them see smoking as a badge which grants them special priviledges. I have no problem with people smoking, as long as I don't have to deal with it. Just like overly loud music, it's an annoyance to others and a sign of disrespect.