I already encountered this issue years ago, when some Chassidic guy in full garb, asked me for change to buy food to feed the goats in Central Park Zoo.
I am there in this bright suit & colored shirt, telling him:- Do you realize that this is Chometz Gomur? (& I figured this out myself without the assistance of a rabbi). He was shocked & didn’t want to belief me, but eventually succumbed, and altered his plans he had been planning on, to feed the goats.