I don't think that spotting a scam project is going to be very hard for me except the team was reputable before they turn to scam.
There are so many ways to know what company is looking like a ponzi scheme especially looking at the offer they are presenting to investors on returns. When the return on investment is looking too big or unimaginable so they can get more investors or users, with this sign and other signs, we can easily now that a project offering exorbitant interest is only after scamming investors.
Don't forget that human has some greed factor. A greedy someone will ignore all the red flags and concentrate on the outrageous reward. People who are not enlightened easily fall for this scam. In most cases, the scammers present fake reviews and testimonials which will convince their greedy victims easily.
The best way to avoid Ponzi schemes is to be rooted in ethics and refuse to promote the scheme even if it was to favour you. I had a serious misunderstanding with someone who knew that the system was fake and a Ponzi, he came to me that we should promote the scheme with my influence, to my community and cash out big before the scam exit. There was already a road map of how the exit will happen, but I rejected the bad deal and told him to think about hundreds of people who are going to lose their life savings. There's no difference between him and an armed robber.
So in as much as you can identify a fake project, we should also protect those that cannot identify fake projects by preaching against Ponzi scheme and also not play in when it favours us.