At the Buffalo Trace Distillery, we filtered our bourbon through activated charcoal for several decades. We now chill filter our bourbons (that excludes those that are uncut/unfiltered). We found that charcoal strips both color and flavor from the whiskey. Our quantitative tests showed that chill filtered bourbon was 17% darker than the charcoal filtered product. A blind taste test revealed that the chill filtered bourbon possessed a greater intensity of flavor.
An interesting aside on the Lincoln County Process; when Gentleman Jack is doubled mellowed (?), it is run through maple charcoal again after it has aged. Rather than allow it to drip through 10 feet of charcoal, it goes through about a foot of it. If it ran through 10 feet it would be nearly as clear as when it was distilled! I assume the flavor would wash out as well.