A large company will usually have strict rules about the presentation of its image. For instance, it will only use specific colours, photos and fonts . The reason? Once these signals become familiar to the viewer, it becomes easy to relate to the firm as a known quantity.
The same restrictions and clear definition are required for any appearance of the company's voice. But this is where firms often err.
When they are trying to reel you in as a customer or an employee, they are very personable and friendly. But once you are sold, they become very task-oriented. You're no longer a pal. The only thing that matters is business.
People don't like that sudden about-face from caring about them to caring exclusively about yourself. It makes you seem untrustworthy and dishonest.
So, if you have a friendly voice in your marketing vehicles, including your recruiting communications (your blog, for instance), you should maintain it in all of your ongoing communications as a basic element of your culture.
Note that the same rule holds true for individuals. Most of us don't feel comfortable around people who are really nice -- until they get angry. Then all concern about other people is thrown out the window.
The person who throws the tantrum might excuse it as his way of getting rid of an upset as quickly as possible. But those who are on the receiving end become wary of him.