good post! i found so many people only rewrite an artitlce for many times. it is very difficult for us to detimine the qualtiy if we speak english as second language.
article spinner are softwares which add synonyms of words in your article, and will ruin your article.
Article spinning is a search engine optimization technique by which blog or website owners attempt to manipulate their rank on Google and other search engines. It works by rewriting existing articles, or parts of articles, and replacing elements to avoid being penalized in the Search Engine Results pages (SERP) for using duplicate content. The original articles are often plagiarized from other websites and can often also be copyright infringements if the original article was used without the copyright owner's permission. Reference: http://en.wikipedia.org/wiki/Article_spinning
Article spinning is basically an automating the process of article rewriting to make it look different and unique. bob25 has given you a best example of how the article is prepared for spinning.
In other words, it's not just confined to spinning, but becomes spamming the internet. People who do that, merely cause twice as much garbage for search engines to hash through. It reminds me of the day that our fairly big town had just one phone book, which did the job perfectly. Then other companies came out with other yellow pages. Eventually, companies got stuck with having to buy ads in more than one book, and each book got less for their ads in the long run. From the user's end, it served no benefit other than more complication. I see a lot of website people doing similar. Increasing the number of pages out there, but adding little to the internet that is useful. The sites that truly add original content are the ones worth the most referrals and ranking.
Article spinning works very well. You can write one article, and spin it into twenty unique versions, to use for backlinks to your site, from the article directories. I use "The Best Spinner" software, and I check every spun version in copyscape, before I use it. Copyscape only charges five cents to check if an article is unique, and it's well worth it.
That usually refers to automatically scrambling the wording of a text i.e. by substitution or changing grammar. It gives you more texts of the same article looking unique to search engines.