The current page image for Depraved Dentist doesn't do a very good job of illustrating the depraved aspect of the trope. As someone who is not familiar with the source material, I just see a man who looks vaguely stern and dentist-like. The caption is similarly meaningless to someone not familiar with the source.
The caption needs to be removed, or at the very least re-potholed, to fix the Nightmare Fuel abuse. I'm voting Keep Until Better Image Suggested on the pic...it doesn't exactly say "depraved" but the overall effect is unsettling, and that's good enough for me.
I was actually expecting this trope to have a picture of that guy on it for the Just a Face and a Caption until I followed the link and saw that it was a different guy that I must assume is a depraved dentist...keep until better image suggested.
I must be cruel, but to be kind
That bad may begin, and worse be left behind
Oops - try this one.
Here are some less-JAFAAC images from Little◊ Shop◊. (I haven't found an image of when he gratuitously kicks a patient in the stomach to get him to say 'AAAH', and he has a misleading facial expression when he clamps a patient's tooth, twists it, and leaves it there to move on to the next patient...)