When folks here posted their blocklists, there were a few borderline sites that I noticed. About.com is the notable one that comes to mind.

One of the surprises I encountered setting up my custom search engine* for anime/manga searches was that I couldn't simply toss about.com into the blacklist - because while they did mirror Wikipedia material, they also had hired or otherwise gotten a passel of legitimate manga & novel reviewers!

* http://www.google.com/cse/home?cx=009114923999563836576:1eor...

about.com's content has noticeably improved in the last year or two.

I remember them being an absolutely scuzzy site, just no useful content at all. Lately that has definitely changed, and definitely for the better.