I also know many smokers and they don't seem to give a damn who they blow their smoke all over. Yes, there are the more considerate ones but many of them aren't and I have witnessed them with my own eyes.

One of my former managers had the inside of his car set alight when a driver in front tossed a lit cig butt out of his window and it flew back and got sucked into my managers partly open window and ended up on his back seat.
My current manager who does smoke has been fined twice after being caught throwing cig butts on the ground instead of putting them in a bin. I told him it served himself right.... I'm very much against throwing litter generally.
Even though smoking is prohibited on buses, there were no amount of times when the driver had to tell a passenger at the back to put out their cig because they were trying to puff away in secret...and making the whole bus smell of their crap at the same time.
I also had no amount of people blowing their smoke all over me when I was waiting at bus stops or in the bus station. I'd be there first and they'd come and sit next to me, light up and the smoke would drift my way and all in my face and I'd end up having to get up and go stand somewhere else which was NOT fair.
I drive now so I don't have to put up with buses anymore.
One of my other colleagues regularly smokes in the work building even though she knows it's not allowed. She is also the one whos' GSD died of lung cancer.

In the paper yesterday, there was a piece about a guy who died after setting himself alight whilst having a secret cig in the hospital where it wasn't allowed anyway. He had been smothered in a flammable cream for a skin problem and had been warned that it was flammable and also had been warned not to smoke anymore cigs whilst he was in hospital. Not being able to stop himself and showing total disregard for what he had been told by docs and nurses, he sneaked off to have a smoke, he lit the cig and turned into a ball of fire. I couldn't help but feel it served himself right.

Yes, there are plenty of smokers who do not seem to give a damn about whether other people want to breathe in their crap or not and many people I speak to agree with me on that one. A lot of the time, it is the other people who complain first before I tell them I agree so I know this is a generally growing attitude towards smoking.

Like us, dog may hate the smell of smoke but they can hardly say so can they? It may make their eyes feel dry and tired and their lungs feel sore like it does me when I've been somewhere where there is a lot of smoke. I try to avoid these situations at all costs because of this but dogs living in smoking homes can't.

I know that smokers aren't deliberately trying to inflict cancer and everything else on those around them but they do often seem to value their habit over the health and safety of others like in the number of incidents I mentioned above.

What has this to do with adotping dogs you might say? Well, if these smokers show disregard where other people, children and such are concerned, why wouldn't they show this same disregard with pets?
Some smokers might save it for outside but many wouldn't and I think this is what shelters worry about.

I agree with what Gisele said about maybe encouraging them to smoke outside the house if they adopt a dog but this can't be enforced on a daily basis can it? I wouldn't want to subject any creature to it personally.