Morgan Spurlock has a habit of making light, funny documentaries that tackle subject matter ranging from disgusting (“Super Size Me”) to potentially inflammatory (“Where in the World is Osama Bin Laden?”). While his new film, “POM Wonderful Presents: The Greatest Movie Ever Sold,” doesn’t have quite the controversial bent of his previous works, it’s Spurlock’s best film to date. The film is an even-handed, smart and often hilarious examination of product placement.

With “The Greatest Movie Ever Sold,” Spurlock sets out to analyze the world of product placement in films and TV shows. Planning to fund the film entirely via product placement, Spurlock travels to various companies, first learning what his “personal brand” is and slowly amassing investors for the film.

As always, Spurlock proves to be a watchable figure, milking the brilliant idea to film a documentary about product placement by funding it through product placement. Once a sponsor is on board in the film, Spurlock always manages to find a place for them in the movie, whether it’s the bottle of POM Wonderful he sips on throughout interviews or the JetBlue terminal where he meets with a particularly anti-product placement subject.

Many of his meetings with advertising executives are equally hilarious, especially an extended pitch session in which Spurlock tries to sell POM Wonderful execs on a commercial focusing on the increased sexual vitality pomegranate juice lends its drinkers. Even better is an interview with Hollywood filmmakers such as Quentin Tarantino and Peter Berg (“Friday Night Lights”), who’ve had to deal with product placement, which includes perhaps the best quote of the film from “Rush Hour” director Brett Ratner: “Artistic integrity? Whatever.”

Unfortunately, Spurlock kind of loses focus about an hour into the film, almost as if he realized no one will pay to watch a 65-minute documentary, so he worked in a quick trip to an advertisement-free city in Brazil and a few other, equally forgettable interludes. While Spurlock remains as informative as ever in these segments, and while they’re tangentially related to the film’s themes, they still feel unfocused and reek of filler, especially a long scene in which he views possible poster designs for the film. However, the film picks back up for a rousing final montage, set to the theme song OK Go composed for the film.

Even though it could stand to be quite a bit shorter, Spurlock took a huge step up with “The Greatest Movie Ever Sold,” a compulsively watchable matter-of-fact documentary that never loses its sense of humor and is all the better for it.