Suppose if there are a number of ICOs started for different coins by anonymous developers then how can we find that which one the legit ICO and which one is scam ICO?
Well, as what you have said developer is anonymous. In that name ICO is not legit. All information of the ICO project should be visible and clearly stated in all social media. The platforms also of the ICO project you are going to invest must be original and not copied by any other existing ICO. That is just a basic things to know on how you can say that the ICO you are going to invest is legit.