There are a few books that do it blatantly--Laurie Halse Anderson, for one, seems to pick a glossary of symbolism for each of her books. It's kind of fun, but also a little anvil-ish.

There are also different degrees of author intent--sometimes they're clearly making a point with their story/character, anyway. But when one teacher insisted that EVERY WORD was carefully crafted to fit in with the author's point, I was ... skeptical.

So I guess you do have to start with a rather broad hammer of authorial intent, and then refine it. But I also look sidelong at any AUTHOR who claims to have deliberately put in a lot of Deep Hidden Meaning. Often the author is as surprised as anyone else when the symbolism is pointed out.