The answer to 'my dryer vent is filthy' is that a dirty dryer vent is a common issue that can be caused by lint buildup, bird nests, or other debris blocking the airflow. Symptoms include longer drying times, increased energy usage, and even fire hazards. To solve this, you'll need to clean out the vent thoroughly.
For a DIY solution, you can use a dryer vent cleaning brush or compressed air to dislodge and remove the lint and debris. Make sure to also clean the exterior vent opening to ensure full airflow. However, if the vent is extensively clogged or you're unable to fully clear it, it's best to call a professional HVAC or dryer vent cleaning service to ensure the job is done safely and effectively.