Reading whitepapers was the best way to avoid scam projects. If the whitepaper is great, move on to the product developments status and the team itself. As the last step, I would check the social media communities.
It reduces the risk of meeting a bad project, but there's no 100% guarantee. So many times there were cases when people had said the project had been good but it turned out it was a scam. It becomes difficult to distinguish a real project from a scam cause fraudsters are very tricky today