most people here - regardless of their opinion of Rossi - believe that at least some version of the e-cat actually does produce excess energy. Can anyone explain why they think so?
That's easy to answer. Since the early 90s peer reviewed papers have claimed anomalous heat in the Ni/H system. In contrast, Rossi doesn't have a single peer reviewed paper to his name and has not permitted any successful independent validation the Ecat technology.