Not wearing one's clothes will always be the easiest way to keep them clean.
Ahhh the joys of being a parent!!
..though the not wearing clothes to keep them clean IS a good idea.
My uncle got beautiful rubber boots when he was little, with Spiderman patterns I think. When he went out in the rain and grandma told him this was the time to try them out, he did, proudly, but soon came accross mud. He didn't want to get mud on his beautiful boots! So he took them off and walked accross the mud in his socks.
That happened long before I was born, but grandma is still telling that story.
Children have the exact same capacity for logic as adults. The only difference is adults have a lot more experience to inform their thought processes.
Pekka has little experience of family life, so they're between equals there!