My almost 9 year old does the same thing. She just dumps things (her shoes, backpack, dishes, etc.) wherever she is at that moment, and cleaning up is her least favorite thing to do. She tells me, "I'm just not a neat person, Mom." We thought it was also important for our daughter to learn about money, so we tied her chores to her allowance. We put a certain number of quarters in a bowl at the beginning of the week, and she loses quarters (or more) if she doesn't pick things up. This made a big difference to her, because she loves Claire's in the mall. Sometimes she will set a goal of something she wants to buy, and that helps to motivate her to earn all of her allowance. Finding something that is important to your daughter can make a difference.
Also, I feel that children have to be allowed to make their own choices. My daughter often chooses not to keep her room clean, and I can't force her to clean it. She is going to keep things the way she wants, and she is trying to assert some independence and her own style by doing so. The consequence is that I never pick up her dirty clothes off the floor, and I only wash what's in the basket. Also, she knows she can't play with friends if her room isn't clean, so it gets cleaned once in a while.
You should set a limit when it comes to the rest of the house. She should not be allowed to leave messes in the shared living space of the home. That is a must, for it affects your sanity. You can shut the door to her bedroom if you must.
We must remember that they are only 9, and can't be expected to be adults yet. Since she is your oldest, you have high expectations for her. Allow her some room to be a kid sometimes. Remember that 9 year olds make messes soemtimes. We can't expect them to be perfect, especially since we are not.
Last, sit down with your husband and have a long conversation about this. Decide together how to deal with it. I was having similar tension for a while with my husband always yelling at my daughter about her room, until we both decided that we could let it go. It's not worth ruining your relationship with your daughter. The tween years are difficult enough without having a strained relationship with your parents to top things off.
Best of luck to you.
C.