Maria this info comes from the people I got to know trough my partner, she used to work for this fellow two years back but not anymore because of the danger this has put her in working early in the morning in the dark. There are stories of leaflet workers getting attacked beaten, belongings taking away from them and even their vans set on fire. Yep too crazy of a job if you ask me, for little to no profit.
I can see that you are interested in this whole thing but I am afraid I can not go any further than this. If this is important to you, get someone to follow one of these vans around. Eventually they will have to get back to their base to weigh in their collected bags.
By the way just an add thought, I know that this whole scam is not a right thing to do, but if you look at it from a different prospective good things come out of it too (if not considering the money that these people make for them selfs off, the good of the people who care to support all these charity programs).
For example the poor over seas now get an opportunity to purchase these secondhand clothes which they can now afford. This is not an excuse I know but hey me I’m just writing down what I know.