A little background.
About three years ago, a friend was living with my partner and I. He decided to get a cat, then a year later was forced to relocate to another city and find an apartment where he was unfortunately unable to have pets. He left her with us, and we've been dealing with a fairly major problem since.
For the last two years, if the catbox is not _pristine_, she will not use it, if she uses it at all. There are two other cats in the house, and we've had a single catbox and even two catboxes, but no matter what we do it seems that every day or every second day, she'll leave a "present" on the tile in the laundry room where the boxes are. There are no other suitable locations in the house for a box to go, as the rest of the home is carpeted and there isn't a space where a catbox wouldn't be ridiculously onerous to the humans in the house.
We clean the boxes daily, have tried everything except for an automatic box that we just can't afford (and don't want to buy knowing there's a risk that disposable components may go out of supply) and have noticed that she's recently started to piss on the floor as well.
What can I do? If this can't be solved, I cannot keep taking care of this cat. I feel that cats are members of the family, but I'm at the point where I'd have to consider putting grandma in the home.