Those with the "right" heart condition are going to fall for scams. They generally know nothing about the real message of Jesus, and little about the Bible. For sure, they are not on solid footing. They lack the ability to do their own thinking, let alone to be their own spiritual guides. Not only are they not capable of self-guidance, they are not willing to let Jesus lead them to the point of self-guidance.
Rather, they are lazy to the point where they want others to do their own thinking. Virtually everyone that was recruited (except those recruited under force or threats) was lazy at that point when they agreed to a study. Instead of checking the whole Bible in context, they blindly followed whatever the study book led them. Admittedly, when confronted with such a shortcut, it is human nature to take the easy out and just use the book. And, until the mid 1990s, access to knowledge was limited to those books, books from the library, and whatever they stumbled on. Very few could even know about the existence of Crisis of Conscience, The God Virus, and other material that leads them to at least ask questions.
Those that fit this category are often under duress, leading to this kind of laziness. It is rare to find someone that just lost a family member (especially a child, and especially if it was to violence), is under extreme physical duress, or that Jehovah has successfully prevented from succeeding in society that is willing and able to expend the work needed to research the Bible itself. Usually, they will default to using the Suffer Forever, False Knowledge, or Washtowel Teach books as their template and using the Bible only to back up the book. And especially if they also have limited or no experience with the Bible or other religions.