According to Norman Gortsby in "Dusk," the young man was not a "genius" in "his particular field." What does he mean by that?

In “Dusk,” the young man who sits down on the bench next to Norman Gortsby spins a yarn about forgetting the name and location of the hotel where he is staying. The reason he gives is that he had gone out to buy a cake of soap, got turned around, and could not find his way back to the hotel. However, he also loses the soap and is left with no money and, he claims, no way to find the hotel. Norman sees this as the weakest part of the already improbable story. Annoyed at his misfortune and convinced that he will not get any money from Norman, he walks off. After he leaves, Norman ponders the young man’s limited skills as a con man, his “particular line,” evidenced by not providing himself with the soap.