I write a lot of articles about high-tech forms of fraud, but that doesn’t mean all scams are electronic in nature. Just as a large amount of identity theft starts with dumpster diving, thousands of people still get scammed in person every year.

A recent variation (discussed in this video from CNN) is that criminals will ring your doorbell, claiming to represent an alarm company, and tell you that you’ve been selected for a possible free burglar alarm installation. They will ask to be let in, supposedly to see if your home qualifies and to scope it out for the installation.

What they’re really doing is, in the parlance of every bad robbery movie you’ve ever seen, is casing the joint for a future break-in. They’re making mental notes of where you keep everything.

If they’re slightly less sneaky, they might just rob you on the spot once you let them in. Either way, the situation is extremely dangerous.

The first thing you have to remember is that burglar alarm companies don’t sell door-to-door. They also don’t install anything for random people for free. Call one up and ask them sometime if you don’t believe me. Okay, maybe they’ll have a drawing at their booth at the county fair, but you still have to enter, and they’re not going to just show up without calling first.

The second thing is this: the days of being able to take a stranger at his word are long gone. When someone you don’t know is standing at your front door, you have no way of verifying their story. If you haven’t requested a service (i.e., called a plumber or an electrician), don’t just accept what that person tells you, and never let them in your house under any circumstance.