The answer to 'why is my upholstery stained' is that there are several common causes, including spills, pet accidents, dirt and grime buildup, and even sun damage. Symptoms can include visible stains, discoloration, or a generally dirty appearance.
For minor stains, you may be able to treat them yourself using a mild detergent or upholstery cleaner and a soft-bristled brush. However, for more stubborn or set-in stains, or if the upholstery is delicate, it's best to call in a professional cleaning service. They have the right equipment and expertise to safely and effectively clean your upholstery without causing further damage.