Verify the ID of all visitors
This person used to work as a door-to-door salesman for ADT Security Services. It’s a good idea to spend money on a reliable home security system, but that’s not what the OP wanted to share. He said that homeowners would invite him inside and point out where their valuables were before verifying who he was.
That’s pretty frightening if you think about it. Some smooth-talking individual knocks on your doors, says they’re from a home security company, and you trust them without seeing any ID? At this point, we should all start asking Girl Scouts to ID themselves before we purchase their cookies.