The scam ICO can usually be seen from the non-disclosure of the developer team in answering questions. They will cover up weaknesses or problems. While the ICO who want to open usually want to hold a live AMA (Ask Me Anythings). But this is not a guarantee, because it could also affect other factors.
Yes I agree , most of the fake ICO's that I've known are very confidential they wont disclose the team member they just propose you a project that full of false promises , Whitepaper has lot of grammatical flaws and lot of suspicious things that they will just ignore if you ask them better to stay away on those kind of ICO's.