he accidentally drops the brush, you take the brush, then he pretends to be grateful while offering to polish your shoes.
when you think it’s free, you want your shoes polished, but he ends up asking for a hefty fee after that.
or he accidentally dropped the brush in front of your feet. Then he pretended to apologize. while offering to shine shoes. and the scam continues like the first trick.
when you complain about the price, his friends will come around you so that you are intimidated and want to pay.