The logic applied by propagandists like Joseph Goebbels is what I would call "sophistry". It may sound true and logical on the surface, and its message may appeal to some people - even a whole crowd of people, such that they turn a blind eye to it's logical inconsistencies. But any truly objective observer will be able to spot the lie. Which is why, again, we come back to logic being the only real remedy. Specifically, logic with the goal of elevating the well-being of all sentient beings.

I agree with you that very bad ideas can be circulated under the guise of logic. But I also think that the only real weapon against bad logic is good logic. And its important that we recognize that. The alternative is just a free for all where the only way of mediating ideas is by appealing to group loyalty - which, to me, is an unacceptable solution.