The answer to 'why is my pressure washer filthy' is that your pressure washer can become dirty over time due to a few common causes. The most likely culprits are mineral buildup from the water, leftover detergent, or general wear and tear on the internal components.
Mineral deposits can accumulate in the pump, hoses, and other parts, leading to reduced pressure and a dirty appearance. Leftover detergent or soap can also leave behind residue that makes the pressure washer look grimy. Additionally, normal use can cause parts to wear down, which can impact the performance and cleanliness of the machine.