Image via Wikipedia1. When you think you are as clean as the fresh-driven snow, you're not.
2. When someone protests he is as clean as the fresh-driven snow, he's not.
Take it to the bank, Charlie Rangel.
"Come now, let us reason together. Though your sins be as as scarlet, they shall be as white as snow". -- Isaiah, chapter two.
Something else you can take to the bank; however, when you achieve white-as-snowness, it is because you are clothed in His righteousness, not your own -- something all Christians, acutely aware of their sin and shortcomings, long and strive for.