You can check the option to include the site review link (http://sitereview.bluecoat.com/) in every exception. If you do not want to include it in every exception, you can add it manually to specific custom exceptions.
In 6.7.x there is a hexadecimal encoded escape characters under exception page Article ID: 175198
If users encounter a site that is categorized incorrectly, they can go to http://sitereview.bluecoat.com/ to request that it be reviewed.
To use this substitution for all default exception pages, you need to tick "Enable Category Review Message in Exceptions" in Configuration > Content Filtering > General.
To resolve this issue in your custom exception pages, change the URL reference from $(url) to $(exception.category_review_url) which gets populated with the necessary SiteReview URL and this substitution is *not* encoded.