My first circus, I was 4 years old. Not thrilled about the awful music, the smells or the huge elephants, but the minute the clown showed up and looked my way--I went running and screaming and no one could pull me back into the tent again!
Clowns are too happy, unnaturally happy. Their features are exaggerated and the human beneath can almost be discerned. His mouth is not as big as the one drawn on, his eyes are not as big as they are drawn on. We see an incongruity in what they pretend to be and what they are. There may be somewhere in our human DNA a bullshit button when it comes to genuine facial expressions.
How about the real-life John Wayne Gacy? The part-time clown/full-time serial killer?
Need anymore confirmation that clowns are evil? Check this out....
A friend dared me to add to my dark anthology erotica series a story about sex with a clown. I did it, and I think I managed to make it feasible and disturbing. It's part of my series "Philia: Sex in Dark Places" and you can get just that story here "Coulrophilia: Love of Clowns."
On that note, hopefully, I managed to change your mind about clowns.