Spotting Ponzi schemes, HYIP or any other investing scheme designed to scam you is pretty easy.
You just need to know where to look and how to read signs. Also bear in mind that there are some extra elaborate scam attempts.
Signs of standard Ponzi:
1. high guaranteed profits - it is impossible to generate stable high returns, basically anything higher than 20% is totally out of the question and should be avoided
2. Risk free investment - You need to remember that real investing is never 100% risk free, there is always a chance that you will lose the money
3. Zero information, or fake info about people behind the company - if you can't find address, phone number, real name of the CEO or staff, no social media profiles etc - it is a huge red flag.
4. Vague info about what this investment is really about - you need to know how this investment will generate money, you can't conjure money from thin air.
high guaranteed profit higher than 20% are possible depend on the amount of time they give, if they say stupid stuff like 100% in 24H, yes you have a point, but 20% in 1 year sound more reasonable to me
about information given i see that some hyip have evolved they tell you the info and maybe they are true, but still is a scam, so beaware