At most of the soul night I go to, there is always someone who will want to take pics. A lot will take photos of the group they are with & some will also go round the room & take pics of everyone. I think that's fine, just so long as they ask first - then if you give permission for your pic to be taken, you have to accept that it could pop up anywhere - Facebook - Soul Source - anywhere at all. Permission first is the key. If you don't want your pic taking, it's probably easier just to head to the bar/toilet/dance floor/best mate that you just spotted at the other end of the room etc when you see the camera heading in your direction - avoid the situation altogether.