I detest smoking, and always have. That doesn't mean I criticise or look down on those people who do smoke, unless it directly affects me or my family - people are (supposedly) free to do as they like. However, I don't think it's fair to expect non-smokers to breathe and suffer second hand smoke, regardless of whether you believe that part is dangerous or not. The simple fact is that it stinks, makes everything around it stink, discolours everything and, more seriously, is highly addictive and proven to cause/contribute to serious health issues.
My mother smoked around 60 a day until she was expecting me and gave it up overnight - she is still going strong at 83. My father smoked around 10 - 15 a day, occasionally quitting for a few months, and died from lung cancer aged 62. This somewhat proves that smoking isn't universally going to shorten your life, which is why I wouldn't try to preach to people about quitting, but it is still a high risk to be taking.
My biggest hate is the smell. When I visit friends and family who smoke, I obviously notice the smoke and smell instantly, but it is maybe days or weeks later, when I go to wear a jacket that I had worn when visiting them, that I catch that stale smoke smell attached to it, which is even worse than the original smell. It makes me dread visiting some people but I still don't complain because it is their choice and it is in their own house. Those same people are not welcome to smoke in our house and have been politely asked not to, which is our choice in our home. Sadly, some don't visit because they can't go more than an hour without smoking, which shows they are addicted/have no respect/can't be bothered to go outside. Maybe it shows that their priorities are different (I'm not saying that about all smokers) but I don't begrudge that and still visit them.
My next biggest issue is the discolouration aspect. As a decorator, I have refused work on countless occasions because of the heavily nicotine stained ceilings, walls and woodwork. Not only is it a lot more work to thoroughly prepare, in order to achieve a good finish, it again has that stale smell which I despise. I have always initially taken on jobs that have been in smokers' houses but have turned down further work on the ones that I return to a year later to find everything is practically brown - I just couldn't justify doing the hard work, and putting up with the smoke and smell, only to have it looking the same 12 months down the line.
Again, I don't try to stop people smoking but I believe that most smokers don't realise how bad it smells, non-smokers do, and it is 50/50 for former smokers. The health issues are there for all to see but, you pay your money, you take your choice.