Even good ones. Even the ones who aren't demanding, who eat anything you cook, who don't make a mess for you to clean up, who are agreeable about how to spend the day. Even those. If there's someone living in the house for ten days who normally isn't there, it's exhausting. The guest never has the same schedule you do, and you have to modify yours to mesh with his. If you're an early riser and he's not, you have to be quiet in the morning so as not to wake him. You end up staying up later and never get enough sleep. The guest makes more cooking, more clean-up, more doing, because you are trying to entertain him. Even if it's a person whom you are glad to see, whom you want to visit, by the time they leave, it's "Thank heavens".
I have spent the day catching up on ten days' worth of our laundry, because I only washed the guest's stuff last week. Straightening and cleaning the guest room, so it will be ready for the next visitor. Cleaning up the kitchen, cleaning up the house, changing beds, basically doing all the stuff I would have been doing during those ten days. And I'm not done yet. I still have to go to the grocery tomorrow, because there's not a particle of fresh food left in the kitchen. I made mac and cheese for dinner, because I had macaroni in the pantry and milk and cheese were the only staples left over in the refrigerator. I even used the last of the butter. And, besides, I couldn't face cooking another big meal.
After I fold a pile of laundry as big as me, I think I'll collapse in bed.