http://www.doj.state.or.us/releases/pdf/2014_top_ten_complaint_list.pdf
The list includes, unfortunately, 95 investment related complaints. Which is fewer complaints than cable TV companies received. Which I suppose is a good sign.
The most common of these frauds are Pyramid Schemes, which peter out when there are finally too many existing participants to support by ripping off new participants:
Pyramid Schemes*
Illegal
pyramids typically involve a few people at the top who get their
friends and relatives to give them money in return for the chance to
recruit more participants. These scams are called "pyramids" because
they depend on an ever-increasing supply of willing participants.
Pyramids inevitably collapse because it is impossible to recruit enough
people to support the scam.
*Courtesy of the Oregon Dept. of Justice.
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