[William Cloud Hicklin]

With regard to 'fading' and Gollum's reaction as opposed to the Ringwraiths:

Tolkien (thru Gandalf) tells us in Chapter I/2 that a mortal who often uses the Ring to become invisible will eventually become fixed in that state permanently; T makes it clear elsewhere that Smeagol/Gollum never actually wore the Ring much under the mountains, it being dark and all. Over and above this is the fact that Smeagol is a Hobbit, and therefore "very tough in the fibre;" in a similar way Frodo endured a fragment of Morgul-knofe for seventeen days which would have "swiftly overcome" many mighty warriors of Men.