First, let's check out the room. The conference room is cold - colder than you would expect, colder than the hotel rooms are elsewhere. The organizers collect enough information from you to build a mailing list, beause they can sell those and make money, too. Some conferences are so serious about this they will "junk call" your number during the conference to make sure that they have a good number to call.
The speakers will flatter you for doing what they want, and criticize those not present for not doing what they want. They will get you in a "push-pull", telling you that they "can feel the energy/excitement/enthusiasm from everyone" to make you doubt your own doubts about them with the authority of majority rule, and then a quick pull of flattery because we know that's when to get you in deeper. The real cults will set meeting rules which will include discouraging you from talking to others and networking for fear of criticism: some ban criticism outright as "discouraging trash talk" (this is a technique designed to keep salesmen focused on their customer, not their insecurities, refocused to say that all criticism is illegitimate). Some will make criticism impossible by making knowledge impossible. They invoke "quantum" and other slippery thoughts not as an area of knowledge but as proof that knowledge is impossible (and making anyone in the audience who has actually studied physics wish that they were somewhere else). Some will work to push your ethics downward, saying "you could make more money if you do it this way, but I'm not telling you to do it that way, but these are the words to use if you did," followed by an admonition to watch your ethics. Some knowledge will be on display so that you can say, "If this is true and possibly valuable, what about the stuff they haven't said?" The funny part about that is that you usually don't know what knowledge is widespread and free and what is unique and valuable, and the scheduling of the conference is designed to keep you from finding out.
The purpose of the lecture is to create rising enthusiasm and lower doubts, so that at the end of the conference, when you are tired and thoroughly trained, you will drain your bank account and available credit to buy their courses/programs/tapes (or the greatest scam, a "mentorship program" that allows you to pay for someone to keep flattering you into going along with the program, and maybe buying more later.) Some are unscrupulous enough to pass out scripts to make you raise your credit limits during breaks, and ask attendees who has been successful at doing so, so they know where to focus their enthusiasm. Sales pitches can invoke disappointed spouses, praying children, and the idea that this is your one and only chance.
Are all seminars bad? No. How do you know which ones are better than others? Use the internet, google search, check out the Better Business Bureau, find out who the principals are and how many companies they have been associated with and what their reputation is, and apply an old maxim: "Leopards do not change their spots." Like all old maxims, it isn't always true, but it's the way to bet. Keep your brains in your heads, ladies and gentlemen, and let's be careful. Don't suppress doubts, don't excuse lies (this rule has wider application).