A: Well of course the simple solution is to get a maid. Remember just because you know of one way to resolve a problem that doesn't mean it is the only way. Even a hypnotist who can use hypnoanaesthesia has the choice of using drugs instead. So you can do all the work on yourself or just get a maid.
Now assuming it is more important to work on yourself than just getting a maid, then how can you go about taking care of this?
Have you ever really looked at your strategy of how you keep things messy? Meaning what do you do on the inside that allows you to keep a room messy. There are many people out there that see a dirty dish and immediately either wash it or place it in the dish washer. What happens when you look at a dirty dish? By going through this process you will discover the difference that will make the difference for you.
Now what's really interesting is that really messy people have mastered negative hallucination. They literally don't see the mess, at least for a period of time. And then when they do, the go into instant overwhelm, and their negative hallucination kicks in again. It's a useful cycle when you want to keep things building up without any conscious awareness of it.
In all the work you have already done, you may have overlooked the simplest one of all, your strategy, the structure of your behavior or pattern.
Start exploring there.
-Oz