One of the webmasters favorite tools:

http://copyscape.com

I bet thats what you meant.

I also scan for footprints. Find a sentence that sounds rather unique (preferably not in the first paragraph) and enter it in google using " ".

Yes! That's it!

However, one question...

If we have most of the sentences in a paragraph copied but with a little paraphrasing or few sentences different, will that be considered wrong or illegal and can be caught through copyscape?

I think so, but there is only one way to find out for sure.

Get a free hosting account, upload the file and point copyscape to the file, then see what it reports.

Content theft is a huge issue. Fortunately engines can't be fooled by replacing a few words and sentences anymore.

I wouldn't consider it legal if someone copies one of our articles, replaces a few idioms and phrases automatically and re-publishes it.

[lecture mode on]

If you do this, you risk getting your page or your entire site banned from google if someone reports you. It also ads no value at all to the net, since this article is just a rip off anyways and can be read elsewhere already. The engines might even ban you automatically, since they know what article was published first. Any article on this site gets crawled within minutes from being published.

Many people don't realize that it is hard work to create a successful website. Search Engines will become smarter and things you can get away with today will bite you in the future. Always remember: The goal of those engines is to provide the user with the most relevant information. Hence they will try to become more and more like humans in reading websites. This means if you write your site for humans in the first place, you have nothing to worry about. Take your time and compose something unique. There are a few new techniques out like "phrase based ranking" or Author Footprints that will help tremendously to reduce the amount of copies.

There is nothing wrong with doing research online by reading other peoples articles. Just don't copy and paste. It's a bit like writing an essay for school. If you are caught copying you will be punished and the punishment is severe enough for you to wonder why you did it in the first place.

[lecture mode off]

One more thing: Just because copyscape doesn't detect it doesn't mean Google doesn't. I didn't know you asked because you wanted to modify an article beyond recognition. IMHO its not worth it.

TT

I think you have to totally rewrite the article by stripping it down to its facts and writing it from scratch.  A lot of people with web sites that need a constant new material will scout for interesting articles, then use that as the basis for their own article.  It's faster than dreaming up something on your own or doing research, and it is easy to hire someone to do the dull rewrite part for you.

Quite frankly none of these concepts make much sense to me.

I have my websites because I have fun writing about things. I don't write for the sake of writing but for the sake of telling stories or sharing experience. For instance I have a lot of tutorials on my website. All are completely genuine and I never ever looked at another website for writing them. I simply shared my experience.

I don't understand why someone would copy something just to have something to babble about. Might as well not do it, since this stuff can be found elsewhere.

Andre

Travel Photography 

I understand what you mean, Andre. I like to write for the sake of writing.