I called the police on an insurance salesman recently.
I answered the door and this guy had a black binder with no writing on the outside. He had no brocures or business card to give me. He had parked his car down the street out of view. And the whole time I talked to him he didn't make eye contact and kept leaning to peek around me and looking all over inside my house. (We have a victorian home with some architectural details and a fish pond, so he could have just been curious, but the guy was just awkward and made me really uncomfortable.)
As soon as I closed the door I got completely creeped out and convinced myself that he was really just some wacko out canvassing houses in the neigborhood to come back later and rob or kill me.
A police officer found him in my neighborhood and questioned him. Apparently he really was an insurance salesman (didn't even know they did that door-to-door anymore) and this was his first day on the job, so he didn't have business cards yet. I felt a little bad for the guy, but the officer reassured me that he thought the guy was socially awkward and he would have wanted his wife to call the police in that situation.