Scams can be stopped only in one way, if total regulation is introduced. Until then, the only thing that we can do is to show the Scam Project at the earliest stages and spread information about it.
If we are talking here at bitcointalk, there are actually a lot of people who does review fake projects and see if they're real. There are also a few threads I found before listing scam projects. But no matter how we keep track of them, there are still some projects that will look legitimate at first but in the end becomes a scam.
Implementing regulation can help but scammers always find ways so the best thing is thorough investigation on each project.