Sounds like she is rather picky but I think we need to consider the other side of the story here.

I realise most times you do have the place tidy. But, even though the occasions are rare, the fact is that she is seeing it when it isn't so. I think it only reasonable that she assume then that it is always the case. I really like the comment above that you document - by pictures - that you are cleaning the house.

As for your art supplies and belongings stretching beyond your own space, she does have a point. However, as you have pointed out that the home is left mostly vacant at the time, maybe you can get permission to use that empty space as an art area - until such time that someone else moves in.

All I am asking is that you try to see the situation as she might be observing it.

I am sure if you approach her there may be a workable solution.