Originally Posted by Janx
I don't know for sure, but I've heard the same explanation you posted (spraying vs vacuum/heating). If it's true, then it's easy to see why the liquid would have more caramelized/unfermentable sugar.
DME always seems to ferment more cleanly in my experience, while liquid stays sweet.
This is from the Hoptech website:
"Some brewers prefer to use dry malt extracts (commonly called DME). They are more easily measured than liquid, but tend to have a higher dextrin content and darker color than the liquids due to the extra drying involved. "
So the drying process seems to actually cause the DME to be darker than the corresponding LME.