One of the speeches at this year's convention addresses get-rich-quick schemes directly. I have taken a page from Blondie's book, and figure if they are talking about it, this is a problem in the society. I agree with ezekiel,
JWs are easy targets for pyramid schemes and the like.
The JW's I have met are anti-establishment. They mistrust major institutions like the United Nations, democracy, the catholic church. They also mistrust traditional medicine, preferring anecdotal evidence and miracle cures. I have heard the weirdest urban legendy stuff from JW's. For example, did you know that the number printed on the bottom of the plastic water bottles tells you how many re-uses it has before it becomes bacteria infected? Also, the best way to preserve youthful, healthy hair is to rinse it in bean-water. The woman who spewed this helpful advice obviously holds a fairly powerful position in the Kingdom hall, considering how the women hung on every word. When she raved over beanwater, however, I did note a flash or two of skepticism from her doting audience. Yes, I would say the JW's are ripe for quackery.
My sister is a doctor. I have learned, by watching her, why doctors are so conservative. They hate losing patients. They therefore tend to stick with tried-and-true remedy, and only switch when a new cure is proven superior.
A JW, on the other hand, will read one article about the dangers of smallpox vaccinations, and yank their kid out of the vaccination program. These same people could peddle a spinach cancer cure based on one convincing testimonial. Don't look at the deep research, gloss the surface. After all, they have been conditioned for it.