@Marco50:
For these guests, you can possibly say you will be tidying up the common areas and if they can please take their personal belongings to their room to avoid anything getting damaged.
For future guests- it could be mentioned in the welcome (if you do it in person) and also in your welcome letter with a message along these lines:
Welcome home. Guests are welcome to store their personal belongings in your designated bedroom along with the closet which is empty and equipped with hangers ready for you to use. Please keep common areas tidy for all to enjoy.