Back in Chapter 1 of the novel, I was scrabbling around for a metaphor for conspicuousness. I came across a great line (attribution lost in the mists of fame): "She stood out like a green tube top in Church."
And there was no point trying to invent anything better than that, because there is nothing better. There couldn't be.
Sometimes you meet perfect phrases like that. There was, and probably is, a punk rocker who took the name "Elvis Hitler." Best punk name ever. Best punk name possible.
And there was, and still is, a Mexican cafe (and "speakeasy") on Columbus Avenue called "Senor Swanky's." An unbeatable ironic nod to the lost night life of 40s and 50s Manhattan, when Ricky Ricardo might have been leading the band while Walter Winchell took notes at a nearby table.
So I eventually came up with something that stands out "like a polar bear in a nunnery." By no means the best paradigm for black and white, but I think there's some compensating humor, first in the sheer surrealism of the situation and then in the isolation of the color contrast, which in real life would be rather down the list of the priorities competing for the attention of the participants. (Boy, there's nothing so unfunny as trying to figure out what makes something funny.)