I read the article it seemed a bit funny at first, but really it makes sense if you think about it. A bottle of soap seems rather innocuous, I find it to be really clever. The things I have seen used as currency, normally in jail, I don't work in drug enforcement, was post it notes, corrugated cardboard chits, patches of cloth bottle caps. Its interesting if you think about it. There is cultural currency even, traded between the different gangs.
This is the first I have heard of the tide thing, it seems like a clunky currency, a shopping cart instead of a wallet. But I guess that is why they use it.
The mind of a criminal is really interesting.