How do you clean set diarrhea stains on the seat of a vinyl toilet seat?

To clean set diarrhea stains on a vinyl toilet seat, start by mixing a solution of warm water and mild soap or a gentle disinfectant. Use a soft cloth or sponge to gently scrub the stained area, avoiding abrasive materials that could damage the finish. Rinse the seat with clean water and dry it thoroughly with a towel. For stubborn stains, consider using a diluted solution of vinegar or baking soda, but test it in a small area first to ensure it won't harm the vinyl.