Random objects spawning in dorm rooms? [NOT FOOD]

You are not supposed to decorate the roommates' corner. They will most times add stuff on surfaces next to their assigned bed. Typically on bedside table, desk and dresser. I don't think they add posters or anything on floor. You can easily (re-)move those items. I'm not sure if they will add new if you remove them, but at least I think they will not dio so until next new term begins.