Clowns are scary.  As someone who is afraid of clowns, I understand why people would hate them so much. It's something about their makeup and their surrealistic way of behaving that makes them so different. The connection to peaceful little-kid things is also scary for me 3/4 of the time. 



Because there have  been only a few cases of clowns actually hurting anyway, this fear is deemed as irrational. Clowns have a certain je ne sais quoi which makes them so incredibly scary. This fear is deeper and therefore more terrifying. But, this is different than thrilling. Thrilling is a one-time scare whereas terror is a deep fright.