Kim has the most delicate sensibilities when it comes to fabric and style. Even on this dreary day, she had donned a thin, simple white tank with a loose, but still light denim button down. All neutrals (even the shoes are a very muted red, which turns neutral), and then that scarf. The bright red (and bold polka dots) of that scarf brings balance to all the neutrals, brings out the slight color in the shoes, and completes the outfit. Every bold patterned/colored scarf should be well balanced with neutrals, especially if you want to highlight the piece and make the color pop.