Does anyone know the meaning of "No Soliciting"

I can see when people walk up to my door and when I'm sure they are trying to sell me something I usually grab my 8 inch chefs knife, answer the door and say I'm busy cutting things. Usually they see the knife and hesitate or take my statement as true and leave. There are some nasty bastages that just won't leave tho and I usually have to close the door on them.