I'm interested in developing a list of questions/variables that are associated with Ponzis.
Here is my short list. Please add items to this list and I'll edit the post.
Ponzi Indicators
1. High rate of return
Explanation: ponzi schemes typically offer very high rates of return that are not possible. Anything that is > 50%/year APR is suspicious. Anything > 500% APR is very suspicious. Ponzis can offer lower rates as well (see Maddoff - 10% APR), but these are less common. ...
I would add that quoting interest rates weekly or monthly, rather than the proper annual rate, is a sure sign of an illicit scheme. It aims at very inexperienced investors.