So this is an old topic, but new to me so I thought I'd post my experiences.
I wanted to do some corn on the cob at the end of my back rib cookout. I love roasted corn on my grill, but I hate tending it so the smoker seemed idea.
I got ten ears of white corn. Half of these I soaked in water (what I usually do for roasting it on the grill). The other half I pulled the husks back, removed the hair, buttered heavily, and then wrapped the husks back on with foil.
I cooked the ribs on the bottom rack. When I opend the smoker to turn them, I added the top rack with the corn on it. It ended up staying on for almost two hours at 225-250 (I wanted it hotter, but it was windy).
The results? The buttered corn was awesome. Ever so slightly overdone, but still wonderful. I suspect that if I followed some of the flavoring suggestions here, it would be even better. The soaked corn was actually underdone. It was ok, but it didn't compare to the other.
I think that the difference was the foil more than the butter. The soaked corn had dried out. I think that the low and slow heat took the moisture out before enough heat could penetrate.
Another important thing was serving it. Because the soaked corn still had the hair on it, I felt like I should clean it before bringing it to the table. This resulted in it being too cold. The foil wrapped corn was the perfect temp.
Foil wrapped is the way to go in my opinion. Now to go wrangle some flavored butter...
-Ernie