This is the same algorithm broadcast networks enact when they try to figure out what shows to pick up: "who does our audience consist of? What would they watch if it were offered? Air things like that." This is why, for example, the History channel shows Ancient Aliens documentaries—they have nothing to do with History; they have everything to do with the particular people who tend to watch the History channel.

You can usually figure out pretty explicitly what cluster you're being assumed to be in, and what it's like, by watching the advertising attached to a TV show or movie. Why do they play SUV ads at Disney/Pixar movies? Because the people in the theatre with money to spend tend to be parents-of-five-year-olds, who often are considering purchasing a new car. Thus, if you told Netflix you had watched a Disney/Pixar movie, it would probably recommend you other media that people in your cluster—people who might buy an SUV soon, to put it one way—would watch.