"The Sweet Smell of Success" was the title of a 1957 film. I believe that it was about a big-shot, go-getter type of person in the USA. The screenplay was co-written by Ernest Lehman (1915-2005). Some sources say that he wrote a novelette with the same title as the film, so that's where the film's title comes from. In his younger days, Lehman wrote advertising copy for a publicity firm that focused on plays and celebrities, and this experience led him to write his novelette, but he decided that that wasn't what he wanted to do, so he got out of advertising and ended up in films. I still don't know how Lehman arrived at the title "The Sweet Smell of Success" for his novelette. I can only assume that he heard someone say it. It sounds like the sort of thing that someone in advertising might say.