Had a lady do that to my house yesterday.
SUV pulls up off to the side of my home and out steps some lady from the Census bureau. How did I know? Because I asked her just what the hell was she doing.
And she lied and said something about how I am the last person to be registered in this area. Didn't realize it at the time but she had a handheld device in her hand that yeah ... certainly looked to have been a GPS unit/palmtop.
And yes I took a picture of her and her car as well.