You will never know when will a project be a pump and dump scam, but to avoid being scammed, I think you'll be needing to be more cautious and read what their project is all about. And if it's too good to be true, you should start doubting already.
The problem is how he can avoid the scam project is there's not a strong indicator to determine which is the scam project? It's easy to avoid the scam project as long as we know how to determine that but it looks like OP is still newbies and he didn't not have a lot of knowledge about this too.