Diablo III designer judges fan screenshots
Diablo III designer Jay Wilson has given a professional opinion of the "fan" screens that darkened down Blizzard's official shots to make them look "grittier." Read in all on MTV.
In a nutshell: some of it isn't possible, some of it may end up looking a bit like it, and most of it would mean you wouldn't be able to see all the enemies and furniture.
Consider yourself told. Now shut up.