Here's a nice candid image of a clown who worked for the Ringling Brothers. The card id's him at Raymond Worth whose stage name was "Flatiron". At least he is not John Wayne Gacy scary. Stay far away from anyone named "Patches the Clown"
Greg, You are quite right about the demand for real photo cards of clowns...I had a small number but after doing a few postcard shows I only had Flat Iron left in that part of my stock. It's somewhat easier to find real photo postcards of the early aeroplane pilots whose appearances at the county fairs attracted large crowds than good images of the clowns. Perhaps working indoors for the clowns limited their chances of being good material to sell such postcards with.