A colleague of mine just sent me a link to glassdoor.com. The site has typical job postings, but it also has reviews. So an employee can go on the site and write a review of the company. For fun, I looked up two of my clients. One only had 2 comments on there but they were pretty scathing ("they treat us like slave labor"). The other had over 75 reviews, none of which were real positive. I also looked up one of Walker's competitors, wow, the reviews were not good.
Now I recognize, the employees that take the time and effort to write a review are probably the ones most upset. However, does that invalidate their complaint? Also, we all know it does not matter if the complaint is valid, it just matters that potential candidates are reading it and gaining a negative perception of the company.
What can HR do with this info? First, they need to be aware this exists and it does not exist just at this site, there are groups on Facebook and LinkedIn for former employees to get together and complain about their company. Once they are aware of the complaints, they can decide if the complaint is valid. If the company has done an employee loyalty/engagement survey recently, did they hear some of the same themes? This would tell you the issue is greater than just a couple of whiny employees.
Second, look up competitors to see what the employees are saying. This may help create a strategic advantage.
Lastly, don't get too discouraged when reading these comments. Even companies that excel at employee loyalty still have employees that are not happy with the company. I have never seen a company with 100% Truly Loyal employees. All you can do is continue to do what you can to make the organziation a better place to work.