Sometimes a beaten-down stock can present a valuable opportunity.While some stocks may trade at cheap valuations for very valid reasons, there's always more than share prices to consider when you're considering a business to add to your portfolio. When you invest in stocks for many years at a time, the list of companies you're willing to put capital into and hold for that long may narrow.Great companies don't suddenly become less so because the tide of investor sentiment shifts. Sometimes, quality businesse ...