Will always looks greasy because he is greasy. Just like a teenager, Will gets up, doesn't shower, grabs whatever's close (even if it's on the floor from last night) and puts it on.
You can see his greasy, unwashed hair under his dirty baseball cap. His face is red and scaly with dead skin. His fingernails are long and dirty because he doesn't cut or clean them.
There's a reason why he thought Crest was soap: he rarely showers or does any personal maintenance.
Look at how much different he looked when he did the TV interview. That's what he looks like when he showers. You can clearly see the difference. It's easy to see that Will showers twice a month maybe.
Dawn is a toddler. Will is a teenager.
