It seems to me there are two types of 'false signs'. One is the false sign that is deception. The other is the false sign that is self-deception. Those people who decieve others are doing it on purpose, and it wouldn't bother them in the slightest that someone calls them on it, since they are into it to for self gain. As long as there are new marks to send money, they'll keep on using the same sales pitch.
Then there are the self-deceived. These people are actual seekers, but they need some kind of reassurance. They believe odd things because it gives them strength in their faith. Many of these people will resent having their beliefs challenged. They are also those people that are the prey of the ones that deceive others. The ones that deceive others prey on the desire of the ones that need reassurance in their faith. The ones that are like that tend to be conservative, distrustful of change, and more comfortable in looking at the past that facing the future.
People will only 'see' the truth about the false signs when they want to. There are people who will be willing to truly examine their beliefs, and many of them will modify their beliefs to some degree. They are all too rare though.