I don't know why but something about the door going when I'm not expecting it makes me a little cross.
I don't like people turning up unexpectedly in case I'm not dressed properly/the house is a mess.
Other than that if its not the postman or a parcel then I often just ignore the door. Can guarantee it would only be sales or something.
Get even more annoyed if they don't go away after the first knock.
I have had a few experiences if pushy salespeople, one even put his foot in the door. Plus I have a really cheeky neighbour, so perhaps this is why.
Anyone else?