Perhaps fear of clowns is a more cultural thing, as in Americans fear them because of they way clowns are often portrayed in popular American culture media. And birthday parties.
If a person holds a job as a birthday party clown for hire, they could be anyone. Because clown makeup hides everything, especially ugly.
I think it would also frighten you, who is not easily frightened, to be play without structure. Like having no safe word and all of your limitations disregarded. Yes...this is resesarch