I was watching an old woman knitting on the subway today, when suddenly she dropped her yarn. It rolled a good five feet, unravelling on the dirty floor of the train; everyone's eyes were drawn to the bright red ball.
Someone nearby handed the yarn back to her. She nodded a thank you, and brushed it off before taking back up her knitting needles.
She couldn't possibly have gotten all the filth of the subway car off of it. The dust and debris will be woven into whatever sweater or scarf she was making. Something no less sweet for the accident suffered during its creation.
It is impossible to always give love that is pure and untainted with mistakes or misapplied intention. Slightly dirty sweaters still keep us warm, though.