those keen-eyed geeks

[Morai]

There are rumours that Túrin wore glasses. He lost them at Nargothrond, and ended up not knowing that Níniel and Nienor look waaay too alike.

I can imagine him saying, "You know, your hair kinda blurs like somebody else I know...."

I have a hunch that Saruman provided the Uruk-Hai with sunscreen and UV-resistant contact lenses, giving them the ability to appear during daylight.