1. Nothing about ethos, but a lot about an attractive return on your investment
This covers 90% of all Blockchain Projects Scams. There were so many proof of stake coins with 10 000% ROI in just a few weeks, but who would buy this coins?
5. Negative reviews on various Internet platforms
I would be careful with this one. EVERY coin and project has negative reviews on some sites. Search for Bitcoin Scam for example
if any project is talking only about the value of their token/coin and not the tech and uses behind it, then most probably its a scam. But yeah, negative reviews don't tell you about being scam or not. Many good projects have negative reviews. There will always be people who will criticize and write negative about things which they don't understand. Warren buffet says whole crypto industry will come to a bad ending. It doesn't make whole industry a scam.