According to reports of Google team, more than 60% of traffic dropped due to content farming, although some of the websites also benefited from Panda. Dynamic URLs make it more complicated because of the auto generated web pages; you should make sure that all the auto/cart generated pages have “NOINDEX”, “NOFOLLOW” because if your website has any copy content then it can affect the original and unique pages.
Have a look at the post from Google which has some specific guidelines for marketers by Google:-
One other specific piece of guidance we've offered is that low-quality content on some parts of a website can impact the whole site’s rankings, and thus removing low quality pages, merging or improving the content of individual shallow pages into more useful pages, or moving low quality pages to a different domain could eventually help the rankings of your higher-quality content.
When it comes to the shallow pages, they are mainly referred as the pages which have very low quality content and don’t have any value. To know more about shallow pages, click here. Almost all the e-commerce websites which were hit by Panda has pages with duplicate content which resulted in shallow page level. Most of the e-commerce websites offer variety of products, for instance, if a clothing store offers products of different sizes/colors and each product will definitely have a separate page.
If your website is offering 30 products in a particular section and that particular product has around 5 sizes and 10 colors, then there will be around 1500 unique pages. Rather than writing 1500 product descriptions ( which is a little difficult), you should write 30 product descriptions for the product page and then use a drop down so that users can pick the right product accordingly.