Who comes to your door and asks questions about your alarm system? 1) A legitimate door to door alarm salesman 2) A burglar Before you answer, ask yourself this: Even if you're sure the person you're talking to is number 1, how do you know they're not also number 2? One doesn't necessarily exclude the other. If you wouldn't tell this personal information to someone cold-calling on the phone, you sure as heck shouldn't tell it to someone cold-calling in person. On a related note, anyone selling "magazines" before 5pm on a weekday is casing houses. That's almost a guarantee. Look out for each other, and call the police/sheriff to report ANY suspicious people or vehicles. Even if you think "well the guy in the van didn't actually DO anything while in my neighborhood", you may have the missing piece of the puzzle the police need to solve a crime in the next neighborhood.