We have a 'do not knock' sticker, care of the gov, and it works.
But yesterday a guy knocked at the door telling me he had been sent to fix the washing machine, I told him she was out.
He gave me a funny look and in his very best Indian accent told me maybe he had the wrong address.
At times such as these there will always be an increase in such attempts, they prey on the vunerable and any one they consider not fully with it.