How to understand is ICO scam or not? What criteria I have to look at? Thanks!
There can be lots of criteria. I can just remind some of them.
1- Look their domain registration, expration date from whois.net . Generally scammers just create a domain for 1 year in 1 month (You will need more proof with this.It can't prove directly, it is scam or not. It can just give additional info)
2- Look at their team. Are their team anonymous? Do they have real contact info and names?
3- Search them on google. (Maybe you can find beneficial info such as a person warns about that ICO or sth)
4- Look at their whitepaper. Do they have one or do they just copy another whitepaper or does their whitepaper look like messy?
5- What is their purpose and what did they achieve for this goal?
You can think more like these. I can't directly say if a ICO has any of this term, it s scam but at least it can make me think twice.