Mike, I had something similiar on my last butt cook and just last week, a rib cook, so I'd like to learn something about it as well.
Before the butt cook, I thought I had used my brass brush inside the lid, but maybe I had forgotten to. Anyway, I opened the lid to check the butts the next morning, and flakes had fell on the meat. I took some vinegar in a spray bottle and spritzed them till they all had washed off. Other than not knowing if I brushed the lid out before hand, I had five butts crammed in there, and had to smoke 'em with all vents wide open all night. That is probably twice as much ventilation as I normally would need. (Incidently, if I ever do five or six again, I will definately skip the water and turn/rotate the three that are on their side.)
Also, I did a rib cook recently and was surprised that I didn't put near enough wood in to keep the smoke going. Anyway, I only added three very small seasoned chunks of wood, one at a time, and the ribs ended up tasting much smokier than usual.
They were ok, and my brother-in-law even said they were some of the best he'd had, but they tasted to me like they had gotten a little bad smoke, and they had. What was strange was that I had to keep all the vents wide open on this cook to get 250, but then they were all done in less than five hours, unlike the usual six. I was relying on the factory gauge that WAS within 5 degrees just a few months ago.
Well, the next day, I noticed a light brown film on the inside of the lid that I haven't noticed before. I also checked the gauge and found out that it's not accurate anymore, reading over 15 degrees too low. That explains why I had to leave the vents wide open most of the cook to get what I thought was 250, allowing more air to the wood to burn too fast.
From now on, I'm gonna really be careful with how fast my wood burns and see if that helps. Other than these two cooks, I've NEVER had anything that pointed to getting bad smoke, and the only thing that was unique about the two cooks was vents staying wide open for most of the low-n-slow cooks. All I can think is that the wood wasn't smoldering "right" like it was with all my previous cooks, "burning" too fast. Who knows? My door is pretty tight, but is there enough ventilation with all three vents wide open for small seasoned wood chunks to eventually flame? I don't want that. I've noticed that my wsm now has a hint of a creosote odor, like my first offset.
Glen's on to something with the water pan, as I haven't had a problem with my hi heat cooks thus far. I typically foil or be extra careful with my smoke in the case of chicken.
Sorry so wordy. Just thinkin' out loud.
