Plagiarism. It's a word that sends shivers down most writers' spines. Most of us diligently ensure that we haven't stolen anyone's work and hope that others do the same for us. Some writers even go so far as to hunt down people who have stolen their words or implement code that prevents copy and pasting on their blog. I used to do this and all I can tell you is it is a BIG FAT WASTE OF TIME.
You're never going to be able to stop people from plagiarising. They'll just keep doing it, even after they are caught. They'll give you some lame excuse about how they didn't know it was illegal to copy and paste your articles or blog posts without your permission. Then, they'll go right back to it. The only real way to stop the thiefs is to sue. And that takes money. Lots of it.
Plus, all of this takes away time from what you should really be doing: writing.
So, am I saying just ignore the sentence snatchers? Yes.
See, beyond bad karma, those that have nothing original on their sites will get penalized by search engines so badly that they won't even show up in results. They won't get any traffic, won't make any money from your work. Eventually, the thieves will slink away into the darkness to find some other way to make a coin.
In the end, you're the winner.