I'll probably get strangled for saying this (because I am putting very traditional gender roles in place) but in the months he was with Michelle, he tended to look neater, tidier, and a bit more well dressed (only a bit). I don't think it was because he was trying to impress her but because she was doing things like buying shampoo, doing laundry, and putting clean clothes in his drawer.
I don't think he tries to look scruffy--I honestly don't think clothes and how they look are anywhere on his radar screen. I think he could care less about clothes. I think if you asked Heath today, "What did you wear yesterday?" he would say, in all seriousness, "I have no fucking clue."
I think we look at things from our frame of reference. For example, if I was going to a movie premiere, I'd be excited--I'd probably go out and buy something new to wear, get a haircut, etc. I think Heath could care less and probably gets a phone call from his publicist an hour before the event, reminding him to go. Heath picks up the nearest pair of dirty shorts from the pile on the floor and off he goes.
Sometimes I wish I could be like that because frankly, I think we place way too much importance on clothes and accoutrements in our society. My 2 cents.
L