Trevor doesn't really care where he lives, i think he's too high on meth (or any other drug) to really care, but Michael can't really live like Trevor because he has got a family to support (also i don't really think Michael would want to live in those conditions anyway.)
Well Michael lives like a pig when his family leave him, smelly old pizza boxes, no maid, etc, so those conditions may suit him more than we mite think. M's story reflects the trappings of material wealth, but I think he's still Mid Western trailer trash at heart.
Wait what? Not having a maid and leaving a pizza box out for a couple days in your MANSION means you live like a pig? Is it really comparable to living in a rusty trailer in the poorest part of the state covered in drug paraphernalia and decomposing food?
I kind of get the point you are trying to make but I believe the only reason Michael cares a little less about his living conditions when his family leaves is because he feels he has nothing to live for, no motivation to clean the house or any of that domestic nonsense, also I think the maid just left because rockstar wanted to do a better job at making the house feel empty in this part of the story and having a maid walking around the place cleaning wouldn't really do well in enforcing that feel.
The maid is quite irrelevant I suppose, but leaving a smelly pizza box with flies there for possibly weeks, not just days, is being a lazy, bone idle, pig IMHO, even at my most depressed times I could throw a f*ckin pizza box in the bin. However, this is just my view on that part of the story, and I agree with your overall POV.
My point really was that I don't see Michael as being that much different from Trevor as far as their true nature goes. Michael is just more driven by material gain, and is therefore, more relatable for most people.