"A Scout is clean. A Scout keeps his body and mind fit. He chooses the company of those who live by high standards. He helps keep his home and community clean."
There's no way to camp, hike, and play in the outdoors and not get dirty. Getting dirty is half the fun, whether it's tramping down a muddy trail or wiping dust off a sweaty brow. If it's not dirt, earth, and grime that makes a Scout dirty, what does? It's a simple chore to scrub dirt off skin, but a much more difficult task to clean up filthy thoughts, habits, and behaviors that accumulate in our lives.
Associating with other people that demonstrate clean minds and hearts is the best way to keep clean. Adult leaders that encourage, praise, and support others are like strong detergent. Scouting with other scouts that cheerfully provide service to the community, help others at all times, and accept responsibility helps keep a scout sparkling clean. Outside of scouting, the choice of friends plays the same role. Hanging out with people that use foul language, have malicious fun, or care only for themselves will ingrain those habits in the scout.