I do the 3-2-1 method on spare ribs and when I go to wrap them at the 3 hour mark they usually look really dark. Nothing like the smooth dark-red color I see from other pics or on TV. I have the WSM and my normal practice is the minion method. Once I dump my lit coals in the center of my pile I scatter 3 or 4 wood chunks on the outside and in the middle of the lit coals. My goal is to get the chunks burning during the wam-up period and eliminate as much as of the bad smoke as possible before putting the food on. I usually let the smoker warmup for about 20 minutes or so, but admittedly there still is some white smoke when the food goes on. After about 30 min or so with the food on, i get my nice blue smoke.
I'm also wondering if my rub might be the reason since I use a heavy amount of brown sugar (only sugar i use), so maybe that is burning or darkening alot? My temps hover in the 225-250 range so i wouldn't think its burning. I'm thinking it has to be the sugar or the fact I still have some white smoke when the food goes on, maybe I'm getting some nasty smoke build up on the food. I have never had any complaints on the taste, but the appearance leaves something to be desired. I can usually hide it with a thin glaze of bbq sauce but I'm tired of using it as a crutch to hide the appearance!!