You asked for a portrait of an old fisherman and got back someone who looks like a mannequin dipped in furniture polish. It happens to almost everyone who generates images with an AI tool, and it is almost never the model's fault. A shiny, plastic look is a combination of prompt habits and the default settings most tools ship with. Once you know what causes it, you can fix it in a couple of passes. If you mostly work with a generative image tool, these fixes will save you a lot of re-rolls.
Why the shine happens
Most image models were trained on a mix of product photography, stock photos, and heavily retouched portraits. That training data is dominated by even, flattering light and flawless surfaces. When you give a vague prompt, the model leans on that average and gives you the airbrushed version of whatever you asked for. Skin loses its pores, fabric loses its weave, and everything picks up a soft specular highlight that reads as plastic.
The second cause is prompt wording. Words like "beautiful," "perfect," "high quality," and "stunning" push the model toward that retouched look. You are literally asking for the polished result. The model has no idea you wanted grit.
Fix the prompt first
Describe material, not just subject. Instead of "a leather jacket," write "scuffed brown leather jacket with visible grain and worn elbows." Instead of "an old wooden door," write "weathered oak door with chipped paint and iron nails." Texture words are what break the plastic spell: pores, freckles, lint, dust, scratches, wrinkles, condensation, fingerprints.
Name the light. Flat frontal light is what makes 3D renders look fake. Ask for a specific direction and quality: "soft window light from the left, deep shadows on the right," or "overcast daylight, no harsh highlights." Side light and backlight both reveal surface detail that frontal light hides.
Drop the flattery adjectives entirely. Replace "beautiful portrait" with "candid documentary portrait in the style of a 1970s film photo." Naming a camera or film stock is one of the fastest ways to escape the glossy default, because the model associates those references with grain and imperfect color.
Add imperfection on purpose
Perfection is the enemy here. Include at least one flaw in every prompt. A stray hair, a chipped mug, uneven stitching, dust on a lens. These small details tell the model that this is a real scene rather than a catalog render. It sounds backwards, but asking for damage is how you get realism.
Change the settings, not just the words
If your tool has a stylize or detail slider, turn it down. High stylize values push toward the polished house style. A lower value gives you a flatter, more photographic base that you can build on. If there is a guidance scale, pulling it down slightly widens the range of what the model considers acceptable and often cuts the shine.
Resolution matters too. Very small images get upscaled with smoothing, which erases texture. Generate larger, then crop, rather than generating small and magnifying.
Post-processing that actually helps
Sometimes the generation is fine and the shine comes from the tool's automatic cleanup. Turn off any auto-enhance or beauty option before you generate. If you are stuck with a glossy result, add grain yourself. A light film grain overlay does more to kill plastic skin than any other single step. Slightly reduce saturation and lift the blacks a touch, because plastic surfaces have crushed shadows and oversaturated color.
Lastly, do not over-sharpen. Sharpening amplifies the wet look on highlights. Soft light and a little grain will read as photograph; crisp edges and glow will read as render.
A repeatable workflow
Write a prompt with material words, a named light direction, and one deliberate flaw. Generate at the highest resolution you can. Check the result and, if it still shines, lower the stylize setting and add a film reference. Apply a grain overlay in any free editor. Three passes at most, and you will have something that looks shot rather than generated. The best images from any AI image generator are the ones where the texture survived the model's urge to smooth everything out.