Permission to use someone’s property isn’t a free pass to do whatever you want.
No matter what kind of relationship you might have with somebody, it is a real privilege if they ever hand over the place they live to you. A home is a sanctuary, and for many people, it takes a lot of trust to be able to share the sanctuary with anyone else. They want to know that it is going to be in good hands, especially if they are not going to be there at the same time as you.
However, it is not uncommon for those who are afforded this privilege to misuse it, causing disagreements further down the line. They have no problem with taking ‘make yourself at home’ a little too literally. Somebody who does not have a place to stay, or at least not a place where they can do whatever they want, can become a nuisance in their desperation to have things their way for once. It is convenient that they do not have to be the ones to clean up the mess or repair any damage. While it is good to be hospitable, we all have to be careful who we share our homes with.