They often recommend the audience invest large and life-changing sums into whatever scheme they are pushing and promise remarkable guaranteed minimum returns ranging from 21 to 24 per cent.
One spiel I've seen was big on dissing banks, financial advisers, accountants, teachers and academia, and newspapers, which were described as peddling untruths. Only the presenter of the seminar was to be believed.
The man, a foreign visitor, claimed to be a multimillionaire, described himself as a financial confidante of Steve Forbes (of Forbes magazine) and former United States President Bill Clinton. If so, why on earth would he have to come to New Zealand to speak to a pathetically small audience of about 20 people?
Why would he need to work so hard to get investors? Surely if it really was such a great investment, he'd have wealthy individuals, or his international high-flying pals, lined up to invest.
As for those returns, anyone who hasn't heard the words "if it sounds too good to be true ..." almost deserves to be parted from his or her money.
The presentation was based on an "investment clock" of the kind I've seen many times at this type of event.
Oddly enough the clock's hands just happened to be pointing to the actual time (six minutes to eight), which was the precise moment to buy before investments would start skyrocketing in the "greed" phase from eight to 12.
I've never seen a seminar presenter suggest it's any time other than the right time to buy.
A basic question for sellers of fail-safe business schemes is why sell the idea if the investment is so good? Often they charge thousands of dollars for people to learn more or join an "inner circle" of investors.
Such presenters do usually have some useful information to impart before they go for the jugular vein.
My advice is if you want to learn from them, don't spend thousands - or even tens of thousands - of dollars to hear their words of wisdom at their seminars.
Instead, buy their books. It is often the case that the books can be a much better investment than the seminars, providing the information for a much lower price.
Almost all wealth or property seminars follow the same process. You're invited to a free session or offered a free consultation. There, the presenter/salesperson works hard at getting you into a trust trap. They tell you lots of "secrets". We're hardwired to want to trust them when they feign trust towards us. I read that in - you guessed it - Forbes magazine. We want to take a risk when we think the person might be genuine.
After softening you up, the presenter/salesperson shows how their investment is far better than anything else on the market. It's invariably your last chance to buy before prices go up. That's exactly what I've seen in local seminars.
Buyers who signed up there and then would have the price fixed in. Because there was limited supply, prices would rise if they didn't hurry. Time pressure means less time to think or ask questions of accountants and lawyers.
Time and time again we see the same modus operandi. Seminars entice people to go along to free introductory seminars where they were groomed to trust the presenter and to believe that they will be their financial saviour.
They are then signed up for seminars costing thousands of dollars, which were not worth more than the cost of one or two of the books.
Even better than buying books from spruikers is to get them out of the library. I've checked, and Auckland Public Libraries has copies of books from a long list of these seminar-presenting characters.
I've been to many "wealth creation" events over the years and had all manner of sales people try to sell me their amazing investments - very few of which haven't subsequently crashed and burned, taking naive investors' money with them.
On the most recent occasion, the audience was interesting. There was a lot of head-nodding throughout and affirmative noises. They liked what they were hearing. Two families had brought their adult children to listen.
It's not just the guy with the $400,000 investment to watch out for. We get conned, legally, out of our money every day by advertising and marketing professionals.
A classic example is the hard selling of products going on in the main thoroughfares of various malls. So much do I hate the sales patter of the mostly young backpackers selling this stuff that I now walk around certain malls instead of going through them - thus depriving other retailers of my spending power.
They build up our trust and we want to believe what they're saying to us. In many cases they offer us what appears a huge discount on the jacked-up original price.
We think they're giving us a never-to-be-repeated offer and we're proud of getting a bargain.
When you're being sold something, anything, it's worth asking: Am I being conned here? That's especially the case with anything sold by smooth patter.
One of the other ways we con ourselves is by not understanding the difference between needs and wants. Parents are particularly bad at this. They believe that little Johnny needs X, Y and Z or his education will fall behind his peers.
Toy stores talk about children's "learning and creative development" and have names such as Love to Learn. This type of language is manipulative. And it works.
Personal finance writers such as myself bang on about needs versus wants. I don't mind anyone buying an iPad, upgraded car, readymade meals, skate shoes, music downloads or whatever - providing they realise these aren't needs.
We also get upsold all sorts of things we don't need. Whether it's McDonald's or the local service station, they will sell us anything to maximise turnover. Who really needs a Coke with their burger when water costs less, is better at slaking thirst and doesn't make them fat.
I'm sure we've all fallen for upsell at some times in our lives.
I stopped using my local AA Service Centre a few years back after an employee admitted that he had sales targets to meet.
That is, he needed to sell extra work to me that I may not have needed. "Doesn't everyone?" he said.