[jstalin]

If only they would downrank sites that exist purely to defame: ripoffreport, stdreport, blacklistreport, etc.

[briandear]

I would add sites that exist to extort in that same category. (i.e mugshot sites, and those “claim your business support site” sites.)

[hiccuphippo]

If only they would downrank sites that exist purely to duplicate content from others: blogs, questions and answers, wikis, etc.