As a devil's advocate--while there is definitely associations classical music with wealth, classical music for evil I don't entirely see. Classical music is a very deep trove of, mostly, royalty free music. Hannibal Lecter listening to the aria from the Goldberg Variations is probably less about signaling his sophistication, and more about the fact that it is a profoundly calm, even serene, piece of music playing during a scene of horrific violence. It mirrors the scene earlier where the said something like "his pulse never got above 80, even when he ate her tongue." It shows the calmness in Lecter despite the violence--this is not a crime of passion or hate.

Another small reference that I think is misused--he mentions Fritz Lang's M, and the "Hall of the Mountain King" melody that the killer whistles. First the film was made around 1931. Classical music would not have that sort of reference to the audience at that time. In my opinion M was the first movie to really understand sound film. The whistling tunes was a way to use sound to evoke presence without the character on screen. We could see a child playing, and hear the whistle in the background, and know that this child was being targeted without having to cut away. We get this kind of film information all the time in movies, but this is the first film that used the technique, and it had nothing to do with classical music. (Lang also invented some other sound dependent techniques in this film.)

This is not to say that some of the other examples are not instance of signaling "bad person" sing classical music, but I don't think its evil. I think the association of classical music with wealth/elitism is well established in modern films, so its presence for a wealthy/elite killer is expected, without taking that to also denoting evil.