Since the most recent Google Panda update, a number of sites have found that their traffic has taken a big hit. Google’s aim was to stop “thin content” sites from ranking; unfortunately, as usual, the definition given by Google is frustratingly vague, and with the update, it may not be so obvious what the issues are.
I’ve compiled a short list of some common reasons sites have suffered after the Panda update. Hopefully, this post gives you a better idea, especially if you are one of those having a difficult time trying to determine the source of your traffic dip.
(Note: I’m assuming that you are running a legitimate site, not scraping and stealing content; otherwise you pretty much have your problem right there already!)

1. Duplicated Content

This is perhaps the biggest issue for legitimate sites that have suffered. It’s obvious that duplicate content can trip the “thin content” flag, but the problem is often quite complicated. For example, modern sites can have a lot of dynamically created pages, different versions of the site, and snippets of text duplicated across the site. If you have an e-Commerce site that has products reachable via several URLs, this might exactly be your problem.
Fixes: Depending on what the issue is, the general rule for duplicated pages is to simply scrap them. Use a 301 redirect to combine all internal duplicated pages to the original one. If you have smaller snippets of text duplicated across the site, then it may be worth taking a look at these as well. This is especially true if they make up a significant portion of your content. If this is the case, then look into reducing the size or scrapping them entirely.

2. High Percentage of Ads/Affiliate Links

If you have a lot of online ads (AdSense) or affiliate links / banners on your pages, then it is highly likely that these are tripping the “thin content” filter. Google states that a page should not have less than 30% unique content, so if your page is composed mostly of ads and little unique text, then this is an issue you need to address.
Affiliate links are a different ball game. Google has been able to detect affiliate links for years now and, in my opinion, they are not good for your rankings. In fact, I never allow an uncloaked affiliate link on my sites and I think that, post-Panda, this is more relevant than ever.
Fixes: My first recommendation would be to add more text as this is likely going to help your ranking and SEO performance anyway. When you have added some unique content, take a look at the page and try to determine whether you think Google would consider it low-quality. Does it provide any value to the reader? Or are there still too many ads on first appearance? If this is the case then I would suggest removing some ads to increase the content ratio.
About the author: Guest post by James Blackwell. James is an SEO consultant for clients such as, an online retailer of jewellery including lovelinks charms.