Well I only read Manchester's post in this thread and I have to agree with lots of it to be honest. Sure, dogs can live without AC, but depending on where you live, if you can't afford it, I don't think you should have dogs either. It's just a matter of good sense, if you won't leave your dog in your car in the sun, you shouldn't leave it in a house that is over 100 degrees either.
I don't personally live in a very hot area, but 2 weeks ago we had a whole week with over 65% of humidity, we lost power for one hour and the dogs were already lethargic and panting a lot. I don't want to imagine what would have happened if the power hadn't come back quick, because the AC in the room made a ton of difference (it's just a window unit).
I've been in arguments about it already too, and I really think that dogs are like children, if you can't afford to take care of them, you shouldn't have any. And that does include being able to pay the vet if there is an emergency (to an extent of course). There are probably just as many irresponsible parents as irresponsible dog owners though unfortunately. I've been flamed for it, but so be it.
In the defense of Manchester though, I've seen so many irresponsible and stupid owners, I don't think it's that surprising if people assume right away that most owners just don't know what they are doing. Even if they post on forums - seriously, I've seen people post things like 'my dog is bleeding a lot, what should I do?' or stories of people crying because they left their dogs outside, one escaped, then the other escaped too a day later because they obviously didn't make sure the second one couldn't escape like the first one did. Seriously, I'm often at a loss for words for this kind of stupidity. Thanksfully it doesn't happen much at all here.
Besides, we all do it to an extent... If you say that your dog is jumping on people, you'll have 10 other posts saying that you should train him/socialize him etc. In my case, nevermind that I've spent 5 months so far trying to fix it, and nothing has worked, and when I got that kind of replies I got really upset, because he's pretty well trained otherwise, and very socialized. But I guess it's normal, people here don't know the others and just assume right away that you are not an experienced owner. It might not be the same tone than Manchester uses, but it's really not that different.