In LOTR, the sword Sting glows whenever goblins or orcs are nearby enough, and in the movies, it can get pretty bright. Can they see this light? If so, has it ever given the wielder away?
Yes. In this passage from The Hobbit, chapter IV, the goblins can clearly see Orcrist and Glamdring. Sting was of the same make, so there is no reason to believe that its light would be any different.
At this point Gandalf fell behind, and Thorin with him. They turned a sharp corner. “About turn!” he shouted. “Draw your sword Thorin!”
There was nothing else to be done; and the goblins did not like it. They came scurrying round the corner in full cry, and found Goblin-cleaver, and Foe-hammer shining cold and bright right in their astonished eyes.
The glow is visible to anyone who can see the blade. However it appears the sheath completely masks the glow as Aragorn is unable to see the blade glowing while it was sheathed.
'Let us see what Sting may show,' answered Aragorn.
Frodo then drew the elf-blade from its sheath. To his dismay the edges gleamed dimly in the night. 'Orcs!' he said. 'Not very near, and yet too near, it seems.’
'I feared as much,' said Aragorn. 'But maybe they are not on this side of the River. The light of Sting is faint, and it may point to no more than spies of Mordor roaming on the slopes of Amon Lhaw. I have never heard before of Orcs upon Amon Hen. Yet who knows what may happen in these evil days, now that Minas Tirith no longer holds secure the passages of Anduin. We must go warily tomorrow.’
The Fellowship of the Ring: Chapter 10 - The Breaking of the Fellowship (emphasis mine)
There is no instance in the books where the glow caused the wielder's presence to become known prematurely.