What are you talking about?
> it all comes from the same place
Which is?
> a small amout of scams
A small number by which metric? Is FTX collapse small? Was Bitconnect small?
> the blockchains are decenteralized and free for all to investigate
What does this have to do with anything? How can you prevent a scam by looking at the decentralized blockchain? At a maximum you can try to read contract source code, but even then only a tiny number of experts would be able to catch potential issues.