When I read it, "rubber baby-buggy bumpers" very clearly means the bumpers on the baby bugger are made of rubber.
Ah, but it's not how the phrase is put together, but what (you assume) it means. In my original, unhyphenated phrase, there's also the meaning that the bumpers are for a buggy made for rubber babies. It's not the structure or the semantics, but some other kind of real-world knowledge (about babies, buggies, and bumpers) that clues you in on the meaning.
How about "the book on the table under the lamp"? I could mean that the book (which I want to draw your attention to) is on the table under the lamp, as opposed to the table under the skylight. Or that the book is the one of the ones on the table, but particularly the book under the lamp, and not the one next to the jar of marmalade. No hyphen or comma or what-have-you will help you there.
