From SearchEngineJournal:

"Duplicate content penalty. Ever heard of it? This penalty is applied by Google and possibly other search engines when content found on your website is largely the same as what is found elsewhere on your site or on other websites across the internet.

Search engine spam has been common ever since search engines were first invented. Search engine spam describes the practice of making changes to your website that gets you listed high in search engines at the expense of readability by humans. Years ago, you could get ranked high on a search term simply by repeating it as many times as possible in a document. The primitive search engines of the past ranked the importance of a keyword simply by counting the number of times a term appeared on a page. Today’s search engines are much more complex."

It's so not worth it to get dumped by a search engine for yarfing up search results; for one thing, if you're going to spend all that hard work on trying to trick the engines, why don't you just re-channel that energy into something more productive? And didn't I sound like a Mom just then? Well, then, listen to your mother. If everyone else in your class decided to spam the search engines would you do it too? No? Then make better choices, sonny. Or so help me I'll ground you until you're 30.

Related:

• What is Black Hat SEO?:Black Hat search engine optimization consists of using unethcial techniques to boost search engine rankings. It's bad, very, very bad.
• Search Engines and Spam: Find out what spamming the search engines is, why you shouldn't do it, and how it relates to search engine optimization.
• Top Five Mistakes in SEO: Find out what not to do when optimizing your site.