Have you been approached, around dusk, by someone knocking on your door trying to sell you a home alarm system? I can’t say that I have, but according to a story in the DMN, that has been happening in growing numbers around Dallas. The story says that door-to-door alarm salespeople are supposed to carry a state-supplied "pocket card" photo ID issued by the Private Securities Bureau, which is probably going to be difficult for most of us to identify not having ever seen one (and not seeing one posted online on the site). As far as I can remember, no one has ever approached our house selling alarms; we get our fair share of magazine salespeople, curb painters, prospective lawn people and down-on-their-luck solicitors, though. Most aren’t particularly scary, and some are downright entertaining, but there’s still a moment of dread when the doorbell rings and the person standing outside isn’t recognizable, and it’s not clear how they arrived.