Hospitality has no rules. Not exactly.
I think hospitality starts in the heart and flows outward from there. If I have a YES kind of attitude, then love and light will radiate from me. If I'm cynical, then even if I work hard at faking hospitality, the other person will sense my distrust or fear and feel unwelcome.
A yes attitude says, "Hey, awesome, here is someone to love." It's a faithful attitude.
A no attitude searches for excuses and focuses on flaws. For example, "This guy looks too much like Albert Einstein so I'm not gonna open the door." or "She's not chatty enough." or "That fat guy wears sweat pants in public and that's disgusting. I don't want him over." or "I'm not going to try and get to know her if she's a Catholic." It is entirely possible to have a no attitude and be full of giggles at the same time. It's also possible to feed someone a gourmet meal and yet communicate hostility or rudeness. That's because hospitality is about more than just food. It needs a personal warmth and flexibility along with it.
I think it's generally acknowledged in our culture that if someone visits our home, it's our responsibility to extend hospitality and that's because many newcomers naturally experience varying degrees of fear about being in a new place. And being outnumbered puts them in a weak position.
If I can put aside my expectations of how I think that person has to behave, chances are he is going to be much more at ease in my presence. But if I'm unhappy with him from the very beginning, it's going to be difficult to gain his respect after that. A first impression, whether nasty or warm or even just... stale, can set the tone for future encounters with that person.
If I'm not ready to accept the new person with a yes attitude, it has more to do with me and my own immaturity or mental blockage than it does with him (or her). It's like being happy to inhale an ice-cream cone when someone hands it to me but not willing to dish out any ice-cream myself. It's not a bad idea to get some help for that.
But all this begs the question. Where does a yes attitude come from?