I've been joining a lot of cyptocurrency Facebook groups and have found most of them to be filled with scams- it's really sad to see how many people fall for them to, usually double your money or MLM scams 
We just have to be aware in some bitcoin groups in facebook that we are joining because nowadays many people are scammers.So that we have to be careful in trusting some people.Don't trust people immediately and before you join in some tradings,you have to assure that it is a legit and not a scam.