If they have a card or brochure they are usually leget. It is usually a method to get more customers, I get a few a year, but I use to get them a lot. After I stick to some of them they hardly come around the house. What they do is go around the neighborhood they are working in,, and let other houses see their work at a house, and if the prospect likes what they have done then they will keep them in mind if the home owner has a future project they can afford. Nothing wrong with that, just be weary of those that dont have any literature or says they can work at you place while you are not home, they will write up a contract for you sign that allowed them to come on your property when you are not home. Dont do that! They will most likely rob you unless you know the guys personally. In my area it is lawn service and driveway and sidewalk cleansers. Also sometimes there is an agreement between two competing operators where for example, 5th street, from 2nd ave to 4th Avenue, one company takes the left side, and other takes the right side, also you may have a guy who does things himself, and takes a few houses down that route, and most of the time the other two dont mind because they lose money, but those are also less houses they have to worry about, so they can take care of their other neighborhoods in the city or county.