Have you tried contacting abuse@craigslist.org? That's where to report things like this.

Flagging software and services would be a violation of their TOS as well (see Use at http://www.craigslist.org/about/terms.of.use).

I haven't used it for those purposes, but Craigslist would also want to know about that type of spam. If you're going to complain about a TOS violation, it's best that you not also violate their TOS.

Give them as much information as possible -- search queries that show the ads from the same person, how you identify it as the same person/entity, and make sure the queries don't have any false positives.

CheckDog will do 100 pages of spell checking for free http://checkdog.com/.Don't know of any place that does grammar checking. I wonder if there are any mechanical turk third party providers that do that?

In my case, I run a forum with thousands of pages of user generated content. I can't afford the spell checking services for that amount of content, and I'm OK with leaving things in the user's original voice. What I did do was go into Google Analytics and export my top content by page title, 500 titles at a time. I copied and pasted the spreadsheet column with the titles into Word, and found the spelling errors in the titles of the posts. I went back and corrected those.

For SEOmoz, I know some of our most popular (in terms of thumbs and comments) posts have been well over 2000 words. Adam, I don't have that post. What I do have is a roundup of 2011 posts by likes, tweets, etc. and you can look at those individually and see length (http://www.seomoz.org/blog/the-best-of-2011-posts-people-who-rocked-our-world).

I'd look more, but I've got a backlog of other Q&A questions due to being on the road. Driving from SF to Seattle today and tomorrow. Halfway there, and way behind on email and Q&A.