The answer to a filthy countertop is to thoroughly clean and disinfect the surface. Common causes of a dirty countertop include spills, food stains, grease buildup, and general daily use. Symptoms may include a sticky, grimy, or discolored appearance.
For a DIY solution, start by clearing the countertop of any items. Use a degreasing cleaner or mixture of warm water and dish soap to scrub the surface, paying close attention to corners and edges. Rinse thoroughly and dry with a clean cloth. For tougher stains, try a baking soda paste or vinegar solution. If the countertop is still not looking its best, consider sealing or refinishing it. If the damage is severe, it's best to call in a professional cleaning service.