For a moment that sounded a bit alien to me, before my memory managed to dig up that I did usually have the Dobermann cross I owned back in the early 90's, on a lead when visitors arrived. But none of my other dogs have cared/does care the same way she did about their home/territory.
With the Spitzes I've owned/owns (Norwegian Buhunds, and Finnish Lapphunds), I would say that their territorial feelings is mostly about alerting about that there is a visitor. Beyond that, a new human, or dog, visitor is just a friend they hadn't/haven't met before.
In general, with my late Smooth Collie and human visitors it was "A visitor, how lovely, mi casa, su casa!" With visiting dogs she really liked some, and with others she was "Meh, I'm going to my Bia bed, wake me up if your human wants to cuddle me."