https://bitcointalksearch.org/topic/how-to-identify-a-ponzi-100696Ponzi 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.
2. Provides no evidence of business activity
They refuse to show what they are investing their capital, what products(s) or services they are selling, and who the customers are. By contrast a mining corporation will be able to provide pictures of hardware and statistics of how many BTC generated per month.
3. Business activity is "speculation"
Speculation doesn't make steady rates of return. In fact the return rate should often be negative.
4. Steady rates of return
When combined with a high rate of return that is greater than the market rate of return this is suspicious.
5. Increasing demand for capital
Unlike a regular business which has its largest demand for capital at the start, the ponzi starts off with a very small amount of capital ("refuses" deposits), and then grows rapidly. An increasing demand for capital makes sense only if the business can show what the money is being used for. A ponzi will need to have its capital grow at a standard rate that exceeds the withdrawals, whereas a legitimate business will have a varying rate of investment (and this rate will often hit zero).
6. Operator hides their identity
If the name and identity of the person who runs this project is publicly known, and they live in a jurisdiction where it would be easy to prosecute them then they are less likely to run away with the money. Though there are exceptions to this (perhaps too many for this to be a good indicator?).
7. A Super Majority of Non-Investors view it as a Ponzi
If a business is only defended as legitimate by those who are invested in it, while the overwhelming majority of individuals who have no money to gain from taking a position see it as a ponzi -- it is likely that the non-investors are more trustworthy in their assessment.
8. They advertise a "Limited Availability"
They have a low demand for funds. Especially in the early phase. Ideally they've got people chomping at the bit to be included in the scheme.
9. They have "Pass-Throughs".
Tentatively this seems like a good indicator. I don't think pass-throughs are typically used in regular project funding. It increases the distance between the investor and the fund-owner and acts as a shield/distraction. It is more indicative of money laundering.