I've contacted the public editor directly in cases that were very clear-cut. Action was taken within minutes or an hour at most... in such cases the paper knows such comments have a small but corrosive action on its reputation, and though not likely, could be named as a co-defendant in a libel suit if it persists in keeping defamatory material online after it has been notified.

Also, most staff recognize when something is over the line. They don't like to host it any more than most people like to read it.