ISKCON'S guru parampara comes madhwa saint. He has written books like mahabharata tatparya(mahabharata's summary) which contains valid explanation for many incidents that took place in mahabharata and ramayana like killing of vali by rama, discarding ekalavya by drona. I think the ISKCON'S book printers should consider to print the madhwa's book such as these. There are many others books that shows the power hari. shrimad venkataramana govindari govinda!!
I think every worldly activites that you do has limitation and legal way of doing it and if we go beyond that the sin would built up. The modern doesn't impose any limitation on worldly activites like sex becuase they do not understand the concept of sin.