Thanks for the reply Tryskell, it's good to have crypto people here!
It's kinda obvious and common sense that those pump signals will be published a few seconds/minutes later to the regular members of the group and the profit will be much smaller than the group owners' and their friends profit because afterall you pay nothing for those pump signals. However even if you receive the signal 1-2 minutes after the start of the pump, you can still make very nice profits for free and get advantage of the pump situation. I don't know what group you've tested but this one works because the pumps are really huge and you can always set a limit price to sell and get advantage of the people who will buy very late, once the drop will start. Moreover, by inviting people you win higher rank which means faster signals. This group have pumped many coins and there are many proofs for everyone to see, and if you feel unsafe you can just observe and don't invest at all. Personally I wouldn't trust a subscription style group unless there are verified big investors in their team, because in order to pump a coin you need a big amount of money.
I didn't post any proofs because I don't want to affect or influence people to invest their money, I just tried this group, it worked for me and I shared it with all of you to test and see (even without investing).