The answer to 'why is my vacuum dirty' is that a dirty vacuum is usually caused by a buildup of dust, debris, and hair in the vacuum's internal components. This can lead to reduced suction power, poor cleaning performance, and even damage to the vacuum over time.
Some common causes of a dirty vacuum include not emptying the dust bin or bag frequently enough, not cleaning the filters, and not properly maintaining the vacuum's brushes and other moving parts. Additionally, using the vacuum on carpets or floors with a lot of dirt, pet hair, or other debris can cause the vacuum to get dirty more quickly.