Juul maintains that its products are for adults, but a former employee told Business Insider that the company's previous ads featured models who were "too close to a sensitive demographic." In addition, the startup threw "a really great party" to launch its devices, the employee said. Bad habits are tough to break. The Juul, an e-cigarette that delivers a powerful nicotine hit equal to the amount in a pack of cigarettes, may be one of the toughest. Adult customers say they find the high nicotine content as satisfying as conventional cigarettes, but the device also has a growing number of teen fans, whose developing brains are uniquely vulnerable to addiction. The Juul's surging popularity am... [Read more]