Basically what it says on the tin. Rather than having all the Clowns in the Circus be completely random physically and mentally more or less the same, maybe have them embody various vices (as is traditional)? For example, one kind might offer to vampirize a sufficiently powerful dwarf, and their appearance would be something that would be obviously potent (i.e. draconic and no shorter than twenty feet at the shoulder), while another might lure away dwarves with the promise of treasure and resemble a malformed Kea, that sort of thing.
Of course, as long as there's still a "tear-off-your-face-and-eat-it-in-front-of-you" subtype, this isn't going to make Circus visits any easier to deal with, but if an individual was encountered, it'd be that much more interesting.