I think you can understand that only from investors. Because big investment companies will not invest scams surely. Other than that you can not trust team section or whitepaper. Because maybe they gave huge money to good devs for writing good whitepapers or they can create fake team with fake linkedins etc.In my opinion investors are the best place for that.
Its our instinct to find it though and some basis is coming from the feedback of early investors. Some scam projects is very noticeable and pretty obvious of their reason why they created for a certain project but sometimes also it is really to detect until when project owners and the team won't show up in telegram and never answering queries.