The answer to 'my vacuum is filthy' is that a dirty vacuum can reduce its suction power and cleaning effectiveness. Common causes include a full dust cup, clogged filters, and accumulated dirt and debris in the hose and brushroll. Symptoms include reduced suction, poor cleaning performance, and visible dirt buildup in the vacuum.
To address a filthy vacuum, you should first check and empty the dust cup. Then clean or replace the filters as needed. You may also need to remove and clean the brushroll and hose. For more stubborn buildup, you may need to disassemble parts of the vacuum for a deeper clean. If the vacuum still isn't performing well after a thorough cleaning, it may be time to have it serviced by a professional.