There's no such thing as a "good" pump group. It's only good if you're actually the owner and the one making calls/signals. Before the owners/admins pump a coin, it's almost guaranteed that they've stocked up beforehand, so they can sell on the way up.
I agree, if you are the owner of this group or you know its owner, then you can assume that it is good group
(for you) but otherwise, it is just like any other pump dump groups.thanks for your opinion