Just a comment I'm throwing out there.......
I have the understanding that by closing the top vent, you're creating a "log-jamb" with the smoke, which backs up inside the smoker. This smoke, not being able to exhaust itself to ambient air, begins to get stale and "burnt" since there isn't a fresh supply of new air coming in the bottom vents.
That is why my top vent is always open....right or wrong...
Meat eater. Woodworker. PS3 Gamer. Home Theater Guy. Beer Drinker.
WSM 22.5 and random cooking stuff used to help form my shapely manly figure.