There aren't a whole lot of companies that have had as impressive a decade as water equipment manufacturer A.O. Smith (NYSE: AOS). On a total-return basis (price appreciation plus dividends), its stock is up an incredible 1,000%. So far, though, 2018 hasn't been as kind, with the stock down about 12% since its highs in January. After looking at the company's second-quarter earnings, it's a little hard to see why Wall Street isn't impressed with what this company is doing.