Citations with dirty data vs Citations that have been cleaned up. If your citations look like the good rather than the bad & ugly, then you don't need to sign-up. HOWEVER, if you can't tell the difference between the two lists, then you need to sign up.
Sign-up to have your bibliography checked and get a perfect score. This usually takes about 45-60 minutes. If you select this option, then you agree to stay until you have made all the necessary changes and have gotten approval from Thurston. Failure to do so will result in a zero for the assignment.