How Do I Know the Usefulness of Amazon's "Frequently Bought Together" Feature?

Somewhere towards the bottom of a given book's info on Amazon, they usually put a "Frequently bought together" list of books, often a two or three book combo of the book in question plus another one or two. Just as their other algorithmic recommendations, these "crowdsourced" recommendations are also usually good. My issue with them is that they may well be a self-fulfilling prophecy if I don't know what the lower numerical bound for "Frequently" is, be it a number, a percentage, etc. Theoretically, you could use an otherwise statistically unacceptable number of bought togethers to "seed" the frequently bought together criteria, and from then on it simply gets reinforced by subsequent buyers who take that recommendation at face value. The reason this is an "itch" for me is that I have a long wish list on Amazon, using Amazon as I do as a bookmark of sorts for books I want to buy at some undefined point in the future. I'd want to trust the FBT thing enough to add the other books, other than the one I wanted, to o wish list as well without having to read their profiles, reader reviews and so on. But I can't trust it if I don't know precisely what "frequently bought together" really means. Any thoughts?