"Dusk" is told by an omniscient third-person narrator through Norman Gortsby's point of view. He is sitting on a park bench watching people. This would seem to characterize him as something of a loner, an introvert, an intellectual, a man with some education who considers himself a philosopher. The young man who tells him his hard-luck story sounds like an English gentleman, and he takes Gortsby to belong to his own social class. Both of them have to work for their livings, but they would only consider doing work appropriate to gentlemen, such as trading in stocks and bonds.
One outstanding character trait of Gortsby is that he is skeptical. This is because he is an urbanite. This is hardly the first time he has sat on a park bench watching the passing parade. A man like him who is fairly well dressed and at leisure is sure to be approached regularly by men, and some women, who have different stories to tell but who all want money. He listens to the young man's story of losing his hotel, but his attitude suggests that he has no intention of helping him out with a loan. He even waits until the stranger has finished with the concluding gambit:
"I'm glad, anyhow, that you don't think the story outrageously improbable."
"Of course," said Gortsby slowly, "the weak point of your story is that you can't produce the soap."
The word "slowly" is significant. It suggests that Gortsby has been listening patiently and evaluating every detail. It also seems to suggest that Gortsby enjoys hearing the different stories people will invent in order to extract money from the gullible; and it further suggests that Gortsby never had any intention of giving the young man any money whether he was telling the truth or not. Gortsby is a little bit cruel, but he has been cheated too often in the past and doesn't mind getting back at one of these tricksters.
Nowadays it is common to hear the telephone ring and to have someone working in a boiler room tell us how they are raising money to help women with breast cancer, or children with leukemia, or perhaps to help wounded veterans. The caller is probably reading a standard pitch off a card, and the funds collected will probably go mostly to those who are raising them. But some of us will listen to the whole pitch, partly for amusement and partly because the caller makes it impossible to get a word in edgewise until he or she is ready to ask for the donation. That is Norman Gortsby. He is a man with a great deal of leisure time, and he is probably lonely, like most unmarried people who live in big cities. He might just as well be listening to this articulate young man as sitting there alone. But he is not a soft touch. He has seen plenty of people like this young stranger get money from one person and then go on to ask for more money from the next likely prospect.
It is only when Gortsby finds the soap that he feels ashamed of himself. The soap convinces him, not only that the stranger was really in trouble, but that he really only wanted to borrow money which he fully intended to pay back as soon as he could locate his original hotel.
Gortsby is not as sophisticated as he would like to think he is. He is still young. He has been conned before and has made up his mind that he is not going to let that happen again. But he is basically what the young stranger took him for, i.e., "a decent chap." He still has some of that "milk of human kindness" that grifters count upon to earn their livings.