You can be as untidy as you like, provided you are not damaging the property. You ls have the right to peaceful enjoyment of the property, so unless there is a sound basis for another visit, they should back off.
If there is mould on the bathroom window it may be the responsibility of the owner to fix it, i.e. if ventilation is inadequate or there are other issues causing it. Or you may need to open the window when you have a shower.