Using color to impart meaning is a common practice among graphic designers and signmakers. Sometimes single colors are applied to entire words; for example, "hot" and "cold" can be depicted, respectively, in red and blue. Sometimes a word will be rendered in many colors, one for each letter, to suggest a variety of flavors.
And sometimes color is used in a manner that resists easy interpretation. Consider the signs of three Korean businesses: Chang's Family Restaurant, Daheen Wang Mandoo (now called Dong's Family Cuisine, with different signage), and Jahn Chi Jahn Chi. Their principal lettering is rendered in a single color, respectively white, black, and blue, but in each case two of the figures are tipped in red. The repeated appearance of this motif suggests some meaning that I haven't been able to fathom.
My inquiries at these businesses (and others, with similar signage) have proved unavailing. If you can shed any light, please do.
Red-tipped Korean script
Various locations, Queens