In my limited experience it has always been caused by poor exhaust airflow. Trying to cook by controling the exhaust instead of controlling the intake air. Caused the smoke to build up inside the smoker and get stale before it could exhaust out.
How y'all are? I'm glad you got to see me I guarontee Justin Wilson 4/24/1914 - 09/05/2001
CAJUN QUE KREWE
KCBS member & CBJ#24398
Twin CoonAss Ugly Drum Smokers
Brinkman Smoke King Deluxe
Brinkman Gourmet ECB with super chicken mods
Weber OTS kettle