If I know someone well enough that I am sleeping at their house, then I know them well enough to say 'should I strip the bed for you?'
I cant find it now, but I just read a funny article about being a houseguest that went over a lot of the common sense things....
~if they dont wear shoes inside, take yours off
~if they are working while you are visiting, stay out of their way until they leve for work (meaning let them shower, coffee, etc before you)
~make yourself at home...dont expect your hosts to wait on you hand and foot. They like you well enough to let you 'live' there, so get your own soda out of the fridge.
~dont use their toiletries, bring your own
~you dont have to do everthing with them, plan some time away (assuming you have your own vehicle). They may be sick to death of tourist things in their area, so you can do that alone which gives them some alone time with their family.