Really more a petty annoyance than a scam, but:
Walking in Istanbul this week, someone passes us and I hear something fall behind us. I turn, this guy has lost a shoeshine brush. So good helpful people that we are, we call, he stops, profusely thanks us and takes it, thanks us some more, takes my hand to shake it, and at the same time he is getting the brush and polish out and going for my shoes, which, BTW, are cloth running shoes.
We saw this happen at least twice more, the brush was not carelessly lost but surreptitiously let go from the hand whole passing someone. Told one of the folks who went for the brush what would happen next, shoeshine guy cursed me.
(My apologies if this is here somewhere already, but it is too much trouble searching on our travel iPad)