Trash bag - Points

We need to credit / compliment / reward trekkers who collect most amount of trash in the Eco bag which is given. I have been on 2 treks as of now in which the trail had a lot of trash but no one really picks up any trash. I had suggested this in both my treks to the trek leaders. This will really encourage ( especially first time or young trekkers ) to collect atleast some amount of trash on the trail. Thank you.