Avoid trouble and do not make any notes about an applicant that could be discriminatory.
For example, a white male applicant for a secretarial position arrives for the interview dressed in a suit. A black female interviewing for the same position arrives wearing sweatpants and a sweatshirt. While it is legally defensible not to hire the black female because of her clothing choice, the reason for rejecting that particular applicant should factually describe that "the applicant appeared for the interview in sweatpants and a sweatshirt."
What the documentation should not be is an open-ended statement that the black female was rejected because she "did not have the proper appearance." The statement is not specific enough and could be interpreted to mean that she was rejected due to race or sex, even if that was not the case.