Having the sense of smell or an enhanced sense of smell is a different process in the mind from being able to descern what those smells mean, as in, this smells 'bad' vs this smells 'good'. If you grew up on rotten meat you'de propably associate that with 'good' even if it still made your eyes water. For the most part I think that their senses and the associations they have have been reduced to an extremely primitive level where a certain smell at best might mean food. It's not that they have to like the smell, but instead like what it gets for them, which would be a full belly.