The answer to 'why is my gutter dusty' is that gutters can accumulate dust, debris, and other buildup over time, especially in areas with a lot of trees, pollen, or environmental pollution. This dust can make your gutters look unsightly and can also clog the system, leading to water drainage issues.
Some common causes of dusty gutters include leaves, twigs, seeds, and other organic matter that falls into the gutters, as well as airborne dust, pollen, and pollutants that settle in the gutters. The dust can also be caused by the deterioration of the gutters themselves, as the material breaks down over time.