The term hacker refers to someone who likes to tinker with hardware or software in an effort to enhance its capabilities. The media and popular culture have twisted the word’s meaning into someone who breaks into computer systems.The different legends about hackers can make them seem like a potential resource for those who feel the need to go beyond the law. Be it as simple as trying to crack an important encrypted file you’ve forgotten the password to, or as devious as keeping tabs on a person’s moves online, there are reasons why a hacker-for-hire might appeal.Finding a computer hacker – for basic password cracking and similar services, at least – is not difficult. A simple Google search for “hackers for hire” will reveal the sites for a number of organizations like Hire to Hack and Hire Hacker. These organizations promise that they can crack databases, emails or websites.
The Positive Aspects of Hiring Grey Hat Hackers
The most obvious advantage to hiring former hackers is that they have real world hacking experience. There are some things that you just can’t learn from a book. Books do a good job of explaining basic hacking techniques. Every hack is different because every network is different. It’s rare for a hacker to be able to use a single technique to gain full access to a network. Often hackers have to combine multiple techniques or apply techniques in a different way than normal to compensate for various network defenses. Only someone with plenty of real world hacking experience can efficiently go from using one technique to another as required by the present situation.
Another positive aspect to hiring reformed hackers as security consultants is that staying up with the latest security exploits and countermeasures is a full time job. In most companies, the IT staff has an acceptable level of security knowledge, but they must focus most of their attention on the day to day responsibilities of keeping the network up and running. A good security consultant focuses almost solely on security and consequently has a level of security knowledge that goes far beyond that of most other IT professionals

Source1:http://www.windowsecurity.com/articles/Hackers-SecurityConsultants.html#
Source2:http://www.makeuseof.com/tag/hire-computer-hackers-online-geeks-weigh
Source3:http://www.processor.com/editorial       /article.asp?article=articles%2Fp2623%2F34p23%2F34p23.asp