I hate to say it, but I don't think you can make someone change if they don't want to, even nicely. I think if you keep nagging and yelling and doing the silent treatment, he may eventually choose to find someone who better tolerates his slobbiness.

You could hire a maid and bill him for it! (They really aren't that expensive, and are _so_ worth it. I went through a couple year period of being able to afford that, with a BF that thought cleaning was not his job, though he was far from messy.)

Nanci