Carver's "Neighbors" is a story about voyeurism: the natural, human tendency to want to live the lives of others and see how others live. The story doesn't suggest this is positive or negative, it just is, and a one-line cliche certainly can't explain a Raymond Carver story.
The story doesn't make value judgments. Given the opportunity to investigate the lives of their neighbors, the husband and wife, but particularly the husband, since the "camera on the wall" point of view follows only him, is aroused, sexually and otherwise. The idea is that, given the chance to do the same, in privacy, we are all like the husband and wife in the story. The story simply presents a kicked-up version of looking into someone else's medicine cabinet.
In short, the story does reveal elements of human character--we are all voyeurs, to an extent. Remember, the couple appears to be completely normal until they get into the neighbor's apartment. The story suggests that they are still being normal, even inside.