Some feel that it is enough for the witnesses to understand a few major doctrines correctly. Whatever doctrines are important to you--trinity, hellfire, the soul, etc--if the JWs are in agreement with your own beliefs on the subject, is that enough to make them a religion worth being a part of?
The Society is fond of using the illustration of a beautifully prepared, tasty and nutritious meal. As you are seated before this meal, your host warns you that a few drops of deadly poison were included with the ingredients. Would you eat the meal?
If this illustration can be applied to other religions, why would it not be appropriate to apply it to the witnesses? If the main body of teachings is correct (debatable, but please, not on this thread) is it acceptable to swallow that which is wrong, bad or dangerous?
Is just being aware that the poison is present enough? Or must steps be taken to remove it? If the poison cannot be removed, what should be done with the meal?
Using the witnesses' own standards, everything they offer must be pure and true or none of it is of value. If some of the "lesser" teachings of JWs are false, of what worth are the others? If it is alright to ignore false teachings in favor of true, then there is no reason this cannot be applied to other religions that have the "important doctrines" correct.
I have heard this illustration used from the platform multiple times. I believe it is also in writing but I do not have access to an updated cd-rom right now. If anyone can post a reference, I would appreciate it.