By Brian O’Connell Successful short sellers need a different, more agile mindset to succeed, Real Money Columnist James ‘Rev Shark’ Deporre argues. It hasn’t been a bed of roses for short-sellers lately. Over the past couple of weeks, “shorties” have been crushed by a fast and furious market rally. As TheStreet’s James “Rev Shark” Deporre often notes, the biggest bounces tend to occur in the worst markets. “That is one of the main things that can make short-selling so difficult,” he said. “Even in the depths of an ugly bear market, an abrupt counter-trend move can destroy well-planned shorts.”…