There's a lot of wild stuff in this movie involving Matteo's machinations, but the weirdest involves his partner at the beginning of the film.
Serious Vampira vibes. I believe this is actress Cathy Marchand, who is uncredited in the movie. On the boat back from the Casino, Stefano asks about their relationship. Matto refers to her as his "slave" and casually mentions that he recently "sold" her just for the experience. Yikes.
At that point Stefano should have said "Well, thanks for the ride, I'll just swim from here," then dived off the boat and freestyled it back to his hotel. Roll credits.
It's not surprising that Matteo, an obscenely wealthy hedonist, has the most decadent wardrobe. Layers and layers of clothes and always with those leather gloves and a floor-length coat around his shoulders. He's not afraid of color, but his fashion sense seems to be based on texture, more than anything else.
While we're here, let's take a moment to appreciate this pair of high-angle interior shots in all their mod 1970's technicolor glory.