They tell a story. The red lipstick mark on my hand, from wiping it off my mouth when I thought I applied it horribly. The darker soda stain on the carpet from that party where you had that awesome dance off. The nail polish on the seat in your car from the summer when you were bored and jumped in, ready to go anywhere.
They may be ugly, but there are amazing stories behind them.
But I can't remember how I got coffee stains all over the notes by the computer.