It might be that you haven't used CS enough to internalize the ethos governing host-guest relationships. I don't think CS hosts generally frame their decision to host someone as providing a favor to this person; rather, this is something they do because they genuinely enjoy it. Speaking for myself, I only expect my guests to be considerate (make little noise, be clean, etc., and show kindness in our interactions). As long as this minimal expectation is met, I take them to be under no obligation towards me.