As you enter the house, greet it. And if the house is worthy, let your peace come upon it, but if it is not worthy, let your peace return to you.
Matthew 10:12-13

"If the house is worthy" doesn't refer to a structure, but to the head of the house and those under his authority. To "greet the house" is to accept them as friends and family in Yeshua. Don't accept hospitality and then remain aloof like a traveling judge.