It's not that hard to be a decent houseguest. All you have to do is sit there and not punch holes in the wall. And even if you do punch a hole in the wall, there are ways to apologize and repay your host. Apparently that's too hard for some houseguests who do unforgivably disrespectful things.
If you're like most people, you have an invisible obligation to be basically decent to the people around you. Politeness isn't required in daily life, but it's typically necessary for someone who wants to get through life as seamlessly as possible. That said, there are loads of social conventions we don't necessarily think about where our desire to get what we want clashes with our desire to not seem rude. Sure, there are generally agreed upon d*ck moves and signs someone wasn't raised right, but these are things that many of us stress over when we don't really have to.