15. A non-transitory computer-readable storage medium storing computer program instructions executed by a computer processor for formatting a user-generated comment for display on a page of a website, the computer program instructions comprising instructions for: retrieving the comment from a repository; determining whether the comment includes a programmatically identifiable watermark; responsive to the comment including a programmatically identifiable watermark, adjusting a spam score associated with the comment, the adjusted spam score indicating high likelihood that the comment is a form of spam; and responsive to comment not including a programmatically identifiable watermark: determining whether the comment is a form of spam; responsive to the comment being spam, adding a programmatically identifiable watermark to the comment; and formatting the comment with the programmatically identifiable watermark for display on the page.
19. The non-transitory computer-readable storage medium of claim 15 , wherein the computer program instructions for determining whether the comment includes a programmatically identifiable watermark further comprise instructions for: identifying the programmatically identifiable watermark based on whether the comment is displayed in a particular font.