The answer to 'why is my grout grimy' is that grout can become discolored and grimy over time due to a buildup of dirt, grime, and mold. This is a common problem, especially in high-traffic areas like bathrooms and kitchens. Grout is a porous material that can easily trap dirt and moisture, leading to the growth of mold and mildew.
Some common causes of grimy grout include improper cleaning, using the wrong cleaning products, and not sealing the grout after installation. Grout should be cleaned regularly with a specialized grout cleaner or a mixture of warm water and vinegar. Sealing the grout can also help prevent future discoloration and make it easier to clean.