She would probably just put them on my bed. She is definitely not passive enough to wash the dishes I put on her bed.
Good idea though.
If she does that, go tougher, throw away all stuff on the bed that is not yours, and store all kitchen stuff that is yours in your room in a cabinet with a lock. Only do your own dishes.
My ex kept toilet-paper on his room, behind a lock, because he was the only one buying toilet paper in the house he lived. After half a year he got fed up with it and locked away the paper for the others. Private property. Did not take that long before the others started buying toilet paper too.