Sam and Smeagol

[Imladris]

Eureka!

[talking about Sam's failure to note the comple change in Gollum's tone at the Stairs of Cirith Ungol] This is due of course to the 'logic of the story.' Sam could hardly have acted differently. (He did reach the point of pity at last (III 221-224) but for the good of Gollum too late.) If he had, what could then have happened? The course of the entry into Mordor and the struggle to reach Mount Doom would ahve been different, and so would the ending. The interest would shift to Gollum, I think, and the battle that would have gone on between his repentance and his new love on one side and the Ring. Though the love would have have been strengthened daily it could not have wrested the mastery from the Ring. I think that in some queer twisted and pitiable way Gollum would have tried (not maybe with conscious design) to satisfy both. Certainly at some pooint not long before the end he would have stolen the Ring or taken it by violence (as he does in the actual Tale). But 'possession' satisfied, I think he would then have sacrificed himself for Frodo's sake and have voluntarily cast himself into the fiery abyss.

Tolkien's letters, letter 246.

Also:

For myself, I was prob. most moved by Sam's disquisition on the seamless web of story, and by the scene when Frodo goes to sleep on his breast, and the tragedy of Gollum who at that moment came within a hair of repentance -- but for one rough word from Sam.

Tolkien's letters, letter 96

Besides, if Sam had such a hatred for Gollum/Smeagol, it would have shone through in his speech and actions, not matter how hard he tried to hide it (and I got the impression he didn't try).