For all its convenience, online shopping’s biggest shortcoming is still the inability to see or test products first-hand before buying. So to feel like we know what we’re getting, we turn to user reviews — something any Amazon shopper is well acquainted with.

Online shopping is often fraught with uncertainly. It might be Robert Downey Jr when you see the photos but you might end up getting Jeffery Dean Morgan instead. But these days, online retailers usually have rating and review systems so real people can leave their impressions on the quality of products. Hearing somebody else's verdict on online goods -- if it's positive -- has the power to put your mind at ease and hit the "buy" button. But perhaps you shouldn't so readily trust the opinions of strangers when you shop online. Here's why.