Thinly-disguised Gay movie
This film is about men who hustle older women for money in exchange for sex and companionship.
Well, that of course happens with older women and younger men, but it happens much more frequently with older gay men and younger gay men.
Given that the original novel is written by a gay man, I'm sure this kind of thing was very familiar to Tennessee Williams. One poster another thread even said supposedly it's about Williams' own experiences in Italy.
There is even a sly wink to the presumed "gay-for-pay" hustlers: when the film first shifts locales to Italy, the narrator explains how the area where Mrs. Stone is about to visit is know for "assignation"; meanwhile, an older man is shown waiting around for someone - when a younger good-looking man shows up. They start talking - exactly when the narrator uses the word "assignation."
"Don't call me 'honey', mac."
"Don't call me 'mac'... HONEY!"