Why are Business Opportunities solicitations such a red flag for folks in this forum?

Is it primarily because they tend to be over priced, crooked, or for some other reason?

I haven’t decided which direction I’m going to go in this business. I’ve attended a Planet Antares seminar one weekend. They were pushing machines for $6,900. I found the same machines on line new for less than half that. Used, for less than a grand.

I’d be really pissed if I had forked over any cash to those people at the seminar.

This week Buzz Bites, an energy snack company, has been giving me calls about their biz opportunity. After researching this forum and others, I'm suspicious of everything.

Are there any biz opportunities in the vending biz that are worth signing up for?