The two or three days around a visit are a quiet test of two people's grace. Whether you are the one arriving with a bag or the one making up the guest bed, a stay under the same roof asks something of both of you. And most of the visits that go sideways do not go sideways over anything dramatic. They go sideways over small, unspoken things that nobody thought to name. So let's name them. Here is the whole art of houseguest etiquette, both sides of it, because a good visit is