Street & restaurant sellers

When I have been in La Marina other nearby areas, I have observed many sellers of goods that travel around the areas offering items for sale, on a few occasions we have seen a man that is deaf & presents a card explaining this.
As suspicious as this may seem, my son has told his friend about an item he bought & his friend told him "it's cool, but my granddad said the man isn't deaf he just pretends to be" I was quite shocked he said this, I hope I'm not just being naïve! ? Does anyone know?