It is simply not true that the smell is disgusting for nonsmokers in general. I know too many nonsmokers who
like the smell of a cigarette outdoors, and will try to get closer if they see someone smoking as they walk by to enjoy the smell. And I'm not a smoker, so it's not selection bias.
Some people are genuinely sensitive to the smell, and will be inevitably replused by it. This isn't that different from people who are especially sensitive to fragrances and get a headache when someone wearing perfume walks by. But I suspect that many more people have simply been conditioned to find the smell disgusting.
It's like beer. Most people don't like beer the first time they try it. Some don't find it disgusting, even at first, but no one likes beer at first taste in the way that people who like beer like beer. But imagine if you were told that beer is disgusting, that it will kill you, and imagine if you were constantly shown pictures of the organs of people dying from beer drinking. Imagine if the people you saw drinking beer were largely delinquents. It would be entirely different, and you would be much less likely to come to appreciate the flavor of beer.