I was looking to create a QR code when I came across this website: http://qrcode.kaywa.com/. It's the number one result on Google for most QR code related searches. Most would assume that's a good thing, right? This website must be doing something right if it gets a page number two on a keyword like "QR code." Let's dig deeper. I went to the homepage - http://www.kaywa.com/ - and found that this company sells mobile marketing solutions to companies. From what I gathered, Kaywa's main business is taking company's web content and making it cell phone accessible. This is slightly related to creating QR codes, but it's not the company's main focus.
I then looked up the site on Alexa. Here's its top search queries and percentage of search traffic:
Kaywa wants people to come to its website that are looking for mobile marketing services, but most of the people who are coming across Kaywa are just looking for a free QR code. There's a disconnect in how Kawya appears to search engines, and what Kaywa is. If I was running this company, I would want to see terms like "cell phone marketing" and "mobile marketing solutions" as top searches.
This is an example of how popular content can still hurt you. SEO and internet marketing are not about getting the most traffic all the time, they're about getting the right traffic. Millions of people a year coming to the site to get a free QR code and then bouncing doesn't help Kaywa's business. Kaywa can still leverage this high ranking content to help it. One thing it should do is move it off its main domain. Then it should link the QR site to it's homepage with anchor text more specific to its core business.
To avoid similar situations on your website, I recommend doing similar search research. Use Google analytics to find out what the most popular content is on your site and what the most popular search queries are. If your results don't align with your core business, consider changing or removing the content.