I have some first-hand experience with Sciento1ogy AKA Dianetics (early 1990s). They use alot of deception and forceful sales tactics to get people in. (Let's just say the best people to work for Scientologists would be successful used car salesmen).
They prey on the weak, directionless, and those with "voids" to fill.
They go door to door. One of the questions they ask is if you've heard of "Dianetics". If you say no, that's green flag #1 for them. (An "unbiased" mind so to speak). They claim to be doing research by administering what they call a "personality" test.
When this happened, I was 21, innocent and prone to depression. I lived in an upper middle class city. I figured why not fill out the test. I had nothing to do. It was just a simple form to fill out and the lady would come back later to check get it. So I filled it out.
There were at least 100 questions. Alot of them were repeated questions worded slightly different. The types of questions indirectly covered things like personal happiness, philosophy, religion, etc. Basically, answers to the questions would easily reveal a person's weaknesses (especially if you are unhappy, not assertive, looking for life answers, things like that).
So then the lady comes back for the test and reveals that they need to process it at their office. So a week later I get a call, and what do you know, you have to come in to their office to get the results of their "test". Oh ok. It would seem my answers raised green flag #2 for them. Probably my lack of religion, my problems with depression (at the time), etc.
I don't know why, but I went.