They are downright creepy. It's actually kind of fascinating how the pick out the people they talk to on the street (I used to work around the corner of their local HQ), it's like watching a vulture circle above a field...
A co-worker almost got roped in by them a few years ago. They gave her a nice long questionaire (multiple choice) to complete within the day and then come back to them. At first she thought she was attending a seminar, but fortunately she talked about it at lunch and our mental alarm bells went off immediately. We went through the papers with her and explained how every single possible answer would require further 'seminars' and that it was definitely Scientology - which she hadn't had noticed yet. Their MO was pretty clever actually. She was out about €400,- already but it could have been a lot worse.