Don't you think that these groups are similar to the pump & dump group? I won't say that all of them are not worthy to follow, even if you follow then they cannot be accurate always. If they prove that they are correct they will ask you to become a paid member. I would always avoid paid signal groups as they always con the member that joins. It is not easy, still, it is possible to make your own calls if you invest a lot of time. Another thing is to gather as much data on the performance of a particular team and players to make a good prediction.
It is not healthy to depend on results from people that you don't know if they are for real or not and not advisable. I have tried it before and I loss big time because a friend gave me the result and it ended up not favourable after the end of the match. It is easy to make your own research and analysis, if you have being following up the games.