Tony Curtis - Vocal cop-out
I'm not a big fan of this movie, but I do own a copy of it.
One big problem with the celebrity guest-villain concept (of Curtis as DeSalvo) is that before De Salvo is captured, when we hear his voice over his victims security systems, it's not Tony Curtis' voice. Apparently the film-makers didn't want to give him away too early, but if they chose an actor instead of a celebrity they wouldn't have had to be dishonest at all.
But this movie is overflowing with dishonesty.