Another approach might be to take a day and clean out that room entirely, top to bottom. Don't say a word about it, that you're having to do it, or say that she better keep it clean. Try to set it up with a lined garbage can and anything else that can help to keep it clean once it's spotless. Look back and say how nice the room looks now it's clean.
It would be interesting to see if she would then make an effort to keep it a bit cleaner since you showed that you care about it.
For a small minority (IMHO) that would work. For the majority it will not...unless...
Every car in our marriage the wife has caused mechanically or body damage due to her disinterest. The last straw was when she HAD to drive to the next town during a major snow storm. Now understand she's self employed, she could have reschedule but she HAD to. I told her with the weather it would be a good day to stay home. NO she HAD too. An hour later I get a call. She was following a string of like minded individuals when a bus was approaching in the opposite lane. She thought the bus was too close so the wife decided to keep her speed up as she moved closer to the edge of her lane. Tires dropped off the edge of the pavement, she over corrected, crossed over both lanes to hit a utility pole. Totaled the car. She said she didn't have any other choices. One she could have stayed home because of the weather. Two she could have taken her foot off the gas, slow down to a stop as she gave the bus more room. I told her I have had it. She now has two choices. Do without a car (I was quickly told that wasn't an option) or SHE could personally pay for the next car. We went car shopping that weekend. I made her go to the bank to apply for the loan. She had to deal with the car salesmen. She had to go the the Bureau of Motor Vehicles for title and registration. Within six months the right rear fender was dented (she backed into a concrete pillar) so bad the trunk wouldn't open. "Who do I call?" she asked. "Remember that insurance card I gave you and told you to in a place you could find it? There is a 800 number on the back to call the insurance company, they will want to know what happen. Because it is "easier" for me and I've dealt with them before I should call..." No, I've stopped being an enabler. You car, your responsibility.
Bless her heart. She was mad when she got off the phone with the Insurance agent. "Why didn't I have car rental on the insurance?" "Because it cost more money. "The deductible, You're paying that, right?" Nope, not my car. "Who's a good body repair shop to get estimates?" Don't know, you have to do your own research.
Within the year another backing accident. Curled the rear bummer into the trunk. "I need to call that same number on that card?", she asked. Yes.
Then there's the dent in the front that you can't see (her explanation). Her reasoning for not having to deal with the insurance and body shop.
Once her pocketbook took a painful hit, she decided to take more care in her driving skills. She set a new recorded for herself. It's been three years without a mishap!!!!!!!!!!!!!!!!!!!!!!!!!
I written all of this to say; Until the person who made the mess is given the proper incentive not to, they will have no reason to stop This applies to children, to co-workers and everyone else.
