I know nothing at all about Tango in Paradise !
But, after reading this thread to this point I feel the need to stick up for groups in general !
Keep in mind that "most" groups are based on a collaboration between a few couples who are friends or are part of a particular
club or site and a travel agent. The travel agent thinks that there is potential to put together a group and reserves a block of rooms.
Then the agent and the friends or site promote the group. Some groups are based on a particular lifestyle interest, but in reality most
are not. Most are open to anyone- they exist simply to provide a way for the people who sign up to communicate and get to know each
other before the trip. Maybe to share some pictures in a dedicated yahoo site, perhaps set up some special activities and themes, etc.
Sure there are regulars/repeaters in these groups but again, in most, the majority of the couples each trip are new ! Most groups are anything
but "closed"- they are all about welcoming new people. There are some who restrict their special activities to group members- but that is really mainly to protect the travel agent who has a financial risk in sponsoring the group by forcing people to book with that agent to participate.
Outside of those special activities though, the people in these groups are just like anyone else at Desire- they are there to meet people and have fun.
They will have gotten to know their fellow group members before the trip so of course they are going to interact with those people more easily- that is the whole point. But they are usually also totally open to meeting and having fun with everyone else.
So if you are there with a group but not part of it - in most cases- it is really up to you. If you want to make the effort to get know the group people and participate as much as you can- you'll generally be welcomed. But you really can't expect to go in with the attitude that they are going to be "clickish" and then expect them to seek you out and change your mind. Can you ?