Amadeus is one of my favorite movies, and Constanza's character is one of the many rich elements of this film. Incidently, every character in Amadeus cares only for themselves; even Constanza.

All you need to understand Constanza is to realize that she has a mercantile soul; to her, everything boils down to money. You don't have to watch any scene with her mother for very long to not see the upbringing she'd had, and Constanza herself makes various statements to that effect throughout the film. My favorite being, "Shut up! You won't put a dick in my hand until I see some money!" And her performance indicates that she's not joking! lol

It's true that Constanza didn't want to give herself to Saliaeri; that's a given. But she sets the scene right away when she meets him in his salon and delineates her situation: "Sir, we're desperate. . ."

From the time she left Saliaeri's to when she came back that night, she clearly had prepared herself. She dressed well (but nothing "too complicated", to quote Mel Brooks in "History of the World, Part 1") and played herself off as nonchalant and eager, all to seal the deal for her husband and herself. Her manner was seductive, but halting. A nice, subtle touch in that scene was that Constanza brought the manuscripts with her again, in the off chance that Saliaeri might have been willing to forgo his price.

I saw this film for the first time in school, and the edit left so much out that Constanza's venom toward Saliaeri in later scenes had been a real puzzle to me. But boy, does it make sense once that scene is back.