basically, duplicate content is a no-no because no search engine wants to list dozens of pages that all say the exact same thing as it brings no value to the searcher. chances are they will pick a few of them out and the rest don't show up in the main index at all.
gogle has duplicate content penalty so your site will be penalized for dup content. its always wise to spend some time writing unique content. but you can also get prewritten articles and use article spinner to re-write them. make sure you proofread if you use that method
I agree with most posts here, in that it's certainly not the best idea, BUT .. I've seen sites with 100% duplicate content get decent traffic. On another site I owned I did a little experiment, I wrote 5 articles and put them on a sub domain, and then copied, verbatim, 5 others, and put them on a different sub domain. 9/10 Articles had been index within a week (in Google); the only one that wasn't was one of the hand written ones.
So:
Copied: 5/5
Handwritten: 4/5
Is it that bad for you? No. Is it the best idea? Also a no.
Keep in mind, that these were on one domain, and the length that the pages were indexed wasn't tested, so there was definitely room for error and inaccuracies.
From what I know, there have been some sites that have had their pagerank really hurt because of sites directly mirroring their site with the addition of the words "Site Moved" to the page.
Not sure where the article is, though, and they might have fixed it by now.
What exactly are you thinking about copying? Getting articles from a site like http://ezinearticles.com/ should not hurt you. It is freely available content for the masses, and their writers have given the publisher the right to use it (credit must be given) I might have missed your point though. Are you talking about going to xyz.com and copying their site content and putting it onto yours, or taking articles from websites like the one I listed and using those one your site?
it might be legal by giving credit where it's due etc, but to answer the op, copied content is inherently bad for seo. you might actually find better luck with copied content if you're copying from a lesser known source that has less iterations in the indices.
the general consensus it that is does hurt. But I think that the duplicate filters from google are overrated. I have seen with my own eyes a site that was copied entirely, 100% design and verything and the copied site had pr3 while the original, being one year older had pr5 . I talked with the owner and he told me he had decent traffic. So, it is better to ahve unique content but don't be afraid from time to time to put something that someone else has...just my 2 cents.
I really do not know on how Google looks @ duplicate content.
Some sites with same content owned by different owners (in some cases) are ranked next to eachother for a keyword, and that too in top 10.
I am also experimenting the samething, not at all for adsnse revewnue or any PPC programs but to see on different search engines, how the ranking and listing goes.
I have made ahuge database. i really mean massive, of about 170 MB of 23000 articles. They used to be in HTML / PHP formats, but converted , categorized and imported them.
AllArticlesFree.com is where you can find the content. I will start playing with the display of the content. Converting to Database will help me change the presentation ofthe content to a large extent.
I've seen sites use completely copied content from places like gamefaqs.com/etc. and rank higher than sites in the same niche with 100% unique content. It isn't fair, but it happens rather often I'm afraid.
Probably it could effect the PR but when it comes to serp I think Google gives more weight to backlinks. So even those sites with duplicate content which has lot of related backlinks rank better than sites with unique content but which dont have backlinks.
on my personal view, i think copied content can affect your sites ranking but not that much. in google, they already removed their supplementary (a result that shows the list of websites with the same content as yours). but unique and fresh content is still a plus for google.
DNKitchen.com and Chef Patrick ---> 
should not hurt you. It is freely available content for the masses, and their writers have given the publisher the right to use it (credit must be given) I might have missed your point though. Are you talking about going to xyz.com and copying their site content and putting it onto yours, or taking articles from websites like the one I listed and using those one your site?
