Comparative study of story dusk by HH Munro and the umbrella by Roald Dahl?

both the stories- dusk by H.H. Munro and umbrella man by Roald Dahl- tell us about confidence tricsters who trick people. in Dusk it is Norman Gortsby and in umbrella man it is the the girl's mother. both of them are very suspicious or you can say they think they are very good at judging people but both of them are fooled. but Dusk is a narrative story( not told by any of the characters of the story) whereas Umbrella man is told by the girl(whose mother is tricked-in the story).