In this 2013 post, I talked a bit about the psychology of the word "free," and how it can lure us into making decisions that aren't necessarily in our interest. In my latest Money Crashers post, I explore this idea in more detail. I talk about how the use of the word "free" affects consumer behavior and give several examples of "free" offers—free shipping, free trials, free gifts with purchase—that end up costing you money in different ways. Then I wrap it up with a few pointers on how to avoid falling into the "free" trap.
As a side note, you may find the title of this piece—How to Avoid Bait & Switch Advertising Scams Offering “Free” Stuff—a little confusing, since the article isn't really about "scams" and is only loosely related to "bait and switch." My original proposed title was "When 'Free' is Too Expensive," but my editor explained that "there really wasn't any search traffic opportunities" for this topic. So instead, he decided to give it a title about "how to avoid bait and switch scams," a topic that attracted "plenty" of search traffic. Ironically, this means the article itself now is a bait and switch scam, because it's trying to lure in people looking for articles on a completely different topic. But at least I managed to talk him into tacking on a reference to the word "free" in the title, so readers won't be completely baffled.