It's fine to wear mismatched clothes you bought in the last three countries you visited, let your hair grow, whatever pleases you but get clean regularly. When you're tired it's easy to decide that there will be time to shower later. Too often that doesn't happen. I've learned to take that shower when I have the chance. Keeping clean makes you feel good - and it helps keep you healthy.
Diseases communicated by touch are common on the road.
Wash your hands in the morning, wash before eating, and wash after visiting the bathroom. In public toilets, many hands have touched every surface, so . . . Train yourself to keep your fingers out of your mouth and avoid rubbing your eyes and nose. Keeping clean helps keep cuts from becoming infected or a fungus from getting a toehold. No one likes taking a cold shower in cold weather or washing out of a bucket, but grit your teeth once in a while to keep clean.