Ask The Consumerists: Wood Filler In Coffee?

Greg wonders:

My friend is a Starbucks “partner”. During his indoctrination…err…training, they told him that mega-mart coffee contains wood fillers and that’s why that coffee is so bitter.

I’ve done about an hour’s worth of internet searching on terms such as filler, bulking, sawdust, and chicory but haven’t found anything conclusive. So, are the major coffee manufacturers filling our coffee with sawdust, or is Starbucks filling their employees heads with lies?”

We bid you, research monkeys, snopesers, and former barristas, what’s the straight scoop on this poop?