The overriding theme of "The Real Thing," as suggested by its title, is that of appearance versus reality, particularly in relation to art. The narrator of the story is a portrait painter, and the plot involves him utilizing "the real thing"—some genuinely respectable, attractive, and formerly aristocratic people, the Monarchs—as the models for his work. However, he later discovers that they are inept as models and that he is much more comfortable using actors who are, in fact, ugly and look less wealthy. While happy to have met these beautiful, formerly wealthy people, they have served no real purpose for him in pursuing his artistry. He also cannot figure out how to portray them accurately: each time he depicts them, they look like themselves rather than the characters he is assigned to portray. Though they are “the real thing,” they are not effective for his purposes. 

Art—or the art people want to see—is not an accurate reflection of real life. People want a portrait or a painting in the age of photography because they have a particular image in mind that they want to see fulfilled. Having "the real thing" is not actually "better" than seeing an image of something presented in the way we expect. Art does not so much imitate life as conceal life, presenting it in a way we would like it to be. The art director of the project that the narrator is working on expresses dissatisfaction with the work thus far—the work that features the Monarchs. Even though the project would theoretically benefit from models like the Monarchs who “look the part,” the opposite is true. Art, therefore, is not completely representative of the authentic experience. Art tells us about our experiences but does not necessarily replace them. 

In detailing his difficulties, the painter explains that the difference between the ugly couple and the beautiful one is that the ugly couple can imagine themselves in any guise, and this helped the painter interpret what he saw. Their power of imagination fueled his. However, the beautiful couple was unable to adequately perform simple duties, and they were unable to present themselves as anything other than a lady and gentleman because they lacked imagination. This can be summed up in a theme: ugly or poor people are far better at adapting to the world in order to present a face it will accept, while rich and beautiful people—who have always been accepted at face value—have never learned these skills and therefore find it very difficult to be anything other than what they are. Though the Monarchs’ position in the past was admirable, without their wealth, they are clumsy. Through attempting to perform tasks that the working class is familiar with, they reveal they lack the skill to do so. When what they are is enough, this is fine, but when they fall on hard times, they will struggle. Humans survive best when they accept that they must "prepare a face" appropriate to every situation. Honesty is not always as valuable—or saleable—as the capacity to adapt.