Investors often look to the decisions of Warren Buffett and his team at Berkshire Hathaway (BRK.A -0.22%) (BRK.B 0.04%), thinking Berkshire's investment decisions can set them up for a lifetime of profits. But even the Oracle of Omaha makes investment mistakes. So what about Berkshire Hathaway's position in Pool Corp (POOL -0.47%)? Is this a long-term winner? Perhaps, but there's a caveat.What does Pool Corp do?Pool Corp is basically a specialized retailer. It sells supplies to build, update, and maintain p ...