Bilbo: an unreliable narrator?

[Aiwendil]

Well, we know that Bilbo was an unreliable narrator in at least one instance - in the version of "Riddles in the Dark" that appeared in the first edition of The Hobbit. Of course, this was not an element of the story originally planned by Tolkien, but was rather an ingenious solution that Tolkien hit upon when he was faced with his plans for the Gollum and the Ring in The Lord of the Rings contradicting what was said in The Hobbit. (We talked about this a little bit in a thread about Tolkien and postmodernism a couple of years ago.)

But that's a particular and peculiar instance. I agree with your larger point. Tolkien never seems to have considered those elements apocryphal, and in fact took pains not to contradict The Hobbit in his later writings. Indeed, the very fact that he bothered to invent the conceit that Bilbo initially lied about how he got the Ring shows that he did not consider the material in The Hobbit to be more generally unreliable.