Overwrought screenplay dialogue with excessive adjectives and flowery descriptions instead of visual storytelling. Directors strip it out during prep.
On set, you'll recognize purple prose immediately: the director flips through the script, closes it, and says, "Let's forget the first page." The problem isn't in the story, but in the execution – the writer has paved the page with adjectives instead of building images. "The beautiful, velvety dawn floods the majestic hall with golden, warm rays of light" is purple prose. "Golden morning light falls through the tall windows" is a script that works.
The core problem: purple prose confuses literary elegance with visual information. A screenplay is not a novel. Your job as a DP isn't to visualize every flowery thought of the writer – you have to realize light, movement, and composition. If the description takes three lines to explain a simple scene, you're losing time. The edit becomes dull because the text has already told everything, instead of showing it.
In practice, this manifests as follows: the writer describes the "gentle, melancholic elegance of an abandoned staircase," but what do you really need? The staircase. The angle. The color tones. The light. Everything else is provided by the visual design – your department, the edit, the music. Purple prose suffocates the space for cinematic decisions. Your gaffer asks, "How hard should the light be?" not "How melancholic?"
It gets worst when purple prose creeps into action writing – endless, ornate descriptions of movement sequences instead of clear sluglines and beats. The director then has to translate instead of direct. This costs set time, patience, and budget. Good screenplays are lean. They say what you see, not how you should feel. You bring the feeling with camera, light, and performance – not by reading adjectives.