The thing to remember about dogs’ ability to show up at the door to welcome you every time is, as I’ve observed on the days I work from home, they have a high false positive rate. So, when Sparky is poised to greet you, tail wagging and prancing with excitement, before you even put your key in the lock, remember that he also got in position to greet the mailman on his daily route, your neighbor when she got home early, and the local drunkard who paused for a moment at your stoop to catch his breath before continuing his ascent up the street.