WotC's Chris Perkins discusses Spelljammer's space clowns in a new video.
Yeah all that, plus the leadl-white base for the faces is associated with disease and death (skull).
Its also significant that a number of old religions (including Egypt and Roman) featured sacred clowns and sacred mask - the clown as otherworldly entity has a very very long heritage
"That was a great campaign, DM!"His villain monologue before the final battle would be weird.