The answer to 'why is my pressure washer dirty' is that a dirty pressure washer is a common issue caused by a variety of factors, such as using the wrong detergent, not properly cleaning the machine after each use, or letting it sit for too long between uses. Symptoms include reduced cleaning power, clogged nozzles, and visible dirt or grime buildup.
To clean a dirty pressure washer, you can try a few DIY steps like flushing the system with clean water, soaking the nozzle, and using a detergent specifically designed for pressure washers. However, if the machine is heavily soiled or has internal issues, it's best to have a professional cleaning technician service it to ensure it's working properly and safely.