The scene where Sylvester is lying unconscious on his bed in the kitchen, and was lowered through a trap door from 1:10 am to 4:00 am is probably the most frightening scene I never watched on a cartoon. They never show what happened to Sylvester, but when he returns, he's changed physically and looks completely traumatized (his fur is white and looks aged, he's not shivering anymore, and his eyes are dilated and with a lost look). Not showing what's in the basement urges you to try to figure it, and you'll probably end realizing the horrors Sylvester witnessed are beyond your imagination. That kind of involvement of the audience is, in my humble opinion, the most elegant form of horror to me!