It's been said that value investing is like shopping in the grocery bargain bin for damaged apples. A bruised apple that costs a quarter is a steal compared to a perfect apple that goes for a dollar. Unless, that is, the bruise on the surface is indicative of an apple that's rotten to the core. Whether you're shopping for bargains at the grocery store or in the stock market, the key is making sure what looks cheap isn't priced that way for good reason.