I want to sell some products that are also prezent on another webshop. They are providing a datafeed with every information about the product, and they have nothing against that i post the info on my webshop.
The question is should i worry about duplicate content? The number of products is to high and it`s not worth rewriteing their description. Will google think that i stole the content?
Depends.
Personally i would prevent Google from indexing DC pages by adding this to the <head>...</head>:
<meta name="robots" content="noindex,follow"/>
The URLs, which come into question, won't rank anyway. So it's (usually) Ok to keep them completely out of Google's sight and don't have to worry any more about all the Algorithm-Updates.
Or, if i have a lot of pages and need more Crawl-Budget, i would use the robots.txt file:
User-agent: *
Disallow: /path/to/affiliate/products/
In this case the Linkjuice cannot flow freely within my site anymore, but all the important pages get indexed. Plus it's incredibly easy to implement. (Just don't do this if you have a lot of deeplinks to your Products from your Homepage etc.)
Matt Cutts in 2009: "Can product descriptions be considered duplicate content?" http://www.youtube.com/watch?v=z07IfCtYbLw He doesn't say "its bad" but he clearly shows that Google doesn't like it.
Matt Cutts in 2012: "Is it useful to have a section of my site that re-posts articles from other sites?" http://www.youtube.com/watch?v=o7sfUDr3w8I States that it's propably a good idea to remove DC Pages (Like content from RSS-Feeds, Press Releases or Product-Description Feeds).
So to make a long story short - I really don't say "start panic" or whatever, i just say "remove everything from your site which could send out negative signals to Google, so you don't have to worry about it anymore" and then you can go on and build up your Brand to sell as many products as possible ;o)