Probably most of us don't pay it much mind, but if you take the time to really observe the characters in Skyrim, you might think you've been transported to the uncanny valley. Their faces are a bit too rough and blurry, their features both too distinct and too generic. It only gets worse with mods, which add detail but no realism. I needn't even mention the lip-syncing.
You get a creepy, uncomfortable feeling, too, when you stop to watch characters, or is it just me?
Mass Effect doesn't have this effect on me, so why does Skyrim?