One of the most effective and simplest way, is through the team.
There are some scam projects that use anonymous team. Whenever I see a thing like that, I quickly take my leave, because as far as I am concerned, it is a red light.
In some cases, the project might have stolen the identity of some innocent people and pose them as the team. This is why you need to search intensely.
Scammers are very smart. A developer might decide to reveal his identity, successfully carry out the ICO to get funds.
He might even go as far as listing on exchange and after some time, since he is holder the larger amount of tokens, he would then dump on investors.
After he might have sold almost everything, the project is termed dead and you hear nothing about the project again.