If the trinket drops during boss farms there is no roll. The group leader just gets the trinket. To see if the group is like this grab a collection and see if there is a roll or if it goes straight to the group lead
last i checked master looter was turned off by default when making a group. also informs people when its on when joining, as well as there has to be a vote to change to master looter. i remember this being a BIG thing during the braniac content when taking down the his prime avatars. did they change it recently?
The last time I had to deal with Master Looter was during AoJ. We were farming the weeklies and the leader kept taking any collections we were picking up. Long story short when we had room in the group I asked for lead to invite a friend, I turned the Looter off and booted the dude from the group.