"Decorating children's wards with paintings of clowns to create a nurturing atmosphere could backfire, research suggests. A University of Sheffield study of more than 250 children, aged four to 16, found the images were widely disliked. Even some of the oldest children found the images scary."
Of course, hindsight is 20/20, but the addition of "festive" red lights in the clowns' eyes was probably a bad idea, and kids these days don't understand why clowns are depicted with four rows of pointy teeth.
All kidding aside, I don't think I've ever seen clowns used in hospital decor. At the Children's Hospital in Fresno, CA, the paintings on the walls were all pairings of animal mothers and children, and all in an 80's pastel palate. Nothing scary about that, unless you find giraffes alarming. I can understand "fun" or "birthday party-ish", but why anyone would see clowns as "nurturing" is beyond me.