http://www.associatedcontent.com/art...of_clowns.html
http://www.wisegeek.com/what-is-coulrophobia.htm
Most agree, however, that the main reasons for coulrophobia are the make-up and exaggerated features of the clown. Painted eyes and painted smiles, as well as the red bulbous nose, can be frightening initially to children. In fact some children share a similar fear of Santa Claus as well.
True coulrophobia usually dates from an initial childhood incident with a clown that provokes intense fear. Many also consider coulrophobia to be a basic dislike or distrust of the painted face of the clown, which obscures true facial expressions.
I was very, very aware of this issue when I was clowning. Our purpose was ministry, we didn't want scared kids, or adults for that matter. We'd often take our wigs off, our shoes off, let the kids play with them and any props we had.
I've seen soooo much good come from clowns used in ministry I can't imagine eliminating them from the toolbox. I just think they need to be used with compassion just like any other thing that's used to reach kids/people.