Very interesting. I had a client, a successful and financially astute entrepreneur who nearly got caught a number of years ago by one of these. He was taken in because an eminent "friend" of his had recommended him to an Irish lawyer (we were never able to check if he was really a lawyer) who was fixing the "investment". We were looking at it dispassionately (without the personal connection element) and could not understand how it worked. All our questions were met with meaningless wordy responses and a patronising tone. Thankfully my client got cold feet and didn't proceed, but he was very taken in by the whole thing.
Best advice - if you are an intelligent and successful person and you do not fully understand how and why something works commercially, and the other party is not able or willing to explain it to your satisfaction, don't touch it. The old cliche, if it's too good to be true it probably is.