The last sentence—I assume this is what you’re referring to—goes “And Jim was sure that in Canterbury, it was regarded as proof that virtue of a certain sort did not go unrewarded. ” Canceling out the double negative, which is deliberate, it means that in Canterbury, a snob town, virtue of a certain sort is rewarded. This is ironic, since Susan Soderborg is a dull girl, and marrying her out of ambition, which is what Bob does, isn’t especially virtuous. Hope this makes things clearer, I don’t see a typo.