Carla hit the nail right on the head with the observation, " They have no clue about their own doctrines in most cases..."
The best way to keep people in a cult is to make sure they don't really understand what they are espousing. Scientology, Wahabi Islam, and UFO cults are other good examples. An old drunk once said, "religion is a snare and a racket."
Throughout the history of the Watchtower there have been "secret doctrines" in the sense that there have been some teachings that were seldom discussed but which were firmly inside the Watchtower doctrinal camp. One of these is that the 144,000 are part of the ransom. Another is the 7,000 year long creative day, which Russell picked up in his early reading - that notion has only the barest scriptural support and can be shown to pre-date Christianity itself.
The Watchtower no longer has Russell, Rutherford or Franz to vigorously defend their "present truth." They are led by a comittee of ignoramuses today, a doctrinal fuster-cluck.