It is hard to know when will the ICO is a scam despite of the trust rating from every different ICO rating sites. As for the least scam ICOs, it should have a rating on at least 3 ICO rating sites. As I know they pay a specific amount for the ICO to be posted and rated. It shows a little sincerity that the ICO is willing to invest an amount for their ICO projects, but this is only one factor for its legitimacy. Since sometimes the ICO become scam on the during between the end, so it is really hard for people to identify it regardless on the finding the team legit (yes sometimes the team is legit and even had KYC approved) but once they become greed on the final moments of the ICO they could do on the money they collected anytime. I can't explain more factors but as for the better part, better choose the ICO participated wisely as possible since sometimes the ICO is good-looking at the start but in the end they have a shady schemes that could make the investors suffer.